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Semi-auto Vortex Cannon! (SUCCESS)

Post questions and info about pneumatic (compressed gas) powered cannons here. This includes discussion about valves, pipe types, compressors, alternate gas setups, and anything else relevant.
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Re: Semi-auto Vortex Cannon!

Unread postAuthor: Anatine Duo » Wed Mar 26, 2014 7:48 am

I did the "hole in the box" toroidal vortex gun using a big coffee can, complete with wood shoulder stock, but did did not get 30' range. Rings were very slow.

Did anyone figure out how the Mattel sonic blaster worked? It could have a long cone in the the main tube.

Has anyone tried putting a cone on the muzzle of a currently working launcher? Shouldn't effect performance of the launcher but could give a neat effect on combustions fired in the dark... add smoke for the pneumatics
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Re: Semi-auto Vortex Cannon!

Unread postAuthor: matti » Wed Mar 26, 2014 1:46 pm

From what I have learned from vortex cannons and rocket engines, you should focus on the nozzle and especially to the nozzle area ratio (exit area/throat area). I used a nozzle area ratio of 100 for my hybrid vortex cannon that creates chamber pressures of about 25bar. I personally think you should have larger then 2" diameter at the exit for use with the pressures your thinking to use.
Also when designing conical nozzles you should have maximum of 30° cone angle (15° half angle), even better if closer or under 20°, otherwise the flow might separate from the nozzle walls.. and you don't want that. :)

Best way to adjust the cannon to get best vortex ring is to use "orifice plate" at the throat of the nozzle (google it) or more specifically orifice paltes, all with different size center holes. If you don't get vortex ring, just try orifice plate with smaller diameter and change to smaller diameter so many times that you get nice vortex ring. don't change pressure, use as high pressure as you can, otherwise your just losing the power that you are able to get from your cannon :wink:
Smaller diameter at the throat gets you higher nozzle area ratio and high nozzle area ratio is what vortex cannons need.

For very low pressures you can use the "hole in a box" or "Whamo Air Blaster" style "inverse" cone.. but not for higher pressures.
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Re: Semi-auto Vortex Cannon!

Unread postAuthor: shiddymunkie » Wed Mar 26, 2014 8:58 pm

matti wrote:Also when designing conical nozzles you should have maximum of 30°cone angle (15° half angle), even better if closer or under 20°, otherwise the flow might separate from the nozzle walls.. and you don't want that. :)


From what I've calculated, my nozzle should have a cone angle of approx 8.6° (4.29° half angle)... is that too acute?

matti wrote:Best way to adjust the cannon to get best vortex ring is to use "orifice plate" at the throat of the nozzle (google it) or more specifically orifice paltes, all with different size center holes. If you don't get vortex ring, just try orifice plate with smaller diameter and change to smaller diameter so many times that you get nice vortex ring. don't change pressure, use as high pressure as you can, otherwise your just losing the power that you are able to get from your cannon :wink:


Sounds like a few washers are in order.

I do have a question though -- what sort of factor does air volume play in a vortex cannon? I get that we'll want to keep PSI and valve speed high, but how many CC's of air do you think it'll take to effectively create and propel a small 2" vortex?
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Last edited by shiddymunkie on Thu Mar 27, 2014 12:00 pm, edited 3 times in total.
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Re: Semi-auto Vortex Cannon!

Unread postAuthor: jackssmirkingrevenge » Thu Mar 27, 2014 5:00 am

matti wrote:"orifice plate"


Image
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Re: Semi-auto Vortex Cannon!

Unread postAuthor: matti » Fri Mar 28, 2014 9:14 am

shiddymunkie wrote:
matti wrote:Also when designing conical nozzles you should have maximum of 30°cone angle (15° half angle), even better if closer or under 20°, otherwise the flow might separate from the nozzle walls.. and you don't want that. :)


From what I've calculated, my nozzle should have a cone angle of approx 8.6° (4.29° half angle)... is that too acute?

matti wrote:Best way to adjust the cannon to get best vortex ring is to use "orifice plate" at the throat of the nozzle (google it) or more specifically orifice paltes, all with different size center holes. If you don't get vortex ring, just try orifice plate with smaller diameter and change to smaller diameter so many times that you get nice vortex ring. don't change pressure, use as high pressure as you can, otherwise your just losing the power that you are able to get from your cannon :wink:


Sounds like a few washers are in order.

I do have a question though -- what sort of factor does air volume play in a vortex cannon? I get that we'll want to keep PSI and valve speed high, but how many CC's of air do you think it'll take to effectively create and propel a small 2" vortex?



I think your Ok with about 200ml chamber, I don't think its a big problem if you adjust your cannon using washers at the throat.
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Re: Semi-auto Vortex Cannon!

Unread postAuthor: shiddymunkie » Fri Mar 28, 2014 8:29 pm

So the cone should be arriving 4/1 or 4/2, but in the meantime I wanted to see what sort of result I could get from a high-pressure/low-volume blast from my setup. The main tank is about 260ml and the chamber is a scant 7.5ml in capacity (the smallest I am able to go, i.e. a single "link" in the expandable chamber design). Pressurized to somewhere between 120-130PSI, I was able to get the below result:

http://s1337.photobucket.com/user/shiddymunkie/media/MVI_8833_zpsec5d0d29.mp4.html


I estimate that the can was about 6in away from the valve opening (not the edge of the PVC adapter). The first shot of air sent the can about 9 feet away before being stopped by the wall, leaving a relatively significant dent. The second shot looks to be about 4 in away from the can, and while slightly less "poppy" in sound, threw the can about 7 feet also leaving a noticeable dent. Not sure what this information tells me, but it sure was fun!

In retrospect, I should have put the can about 10in away (length of the cone) to see what sort of result I could get from that distance...but with only a few days before it comes in, I might just wait for the real deal. How awesome would it be if a chamber that small could produce the vortex I'm looking for? Couple that with a small 13ci/3000 PSI tank + regulator, and were talking hundreds of shots per fill.

[edit]

Welp, I broke down and filmed a 10" distance shot lol. I figured why wait? -- here it is (and sorry for the sniffling, fighting a cold):
http://s1337.photobucket.com/user/shiddymunkie/media/MVI_8834_zpsa3f04055.mp4.html

If that's the force the air has after traveling 10" through open space, I imagine that same blast of air would retain even more power through a 10" cone, theoretically giving a vortex a good "push" to go longer distances/hit harder.
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Re: Semi-auto Vortex Cannon!

Unread postAuthor: jackssmirkingrevenge » Sat Mar 29, 2014 8:13 am



Damn that is one enormous slide valve!
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Re: Semi-auto Vortex Cannon!

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Re: Semi-auto Vortex Cannon!

Unread postAuthor: shiddymunkie » Sat Mar 29, 2014 1:48 pm

jackssmirkingrevenge wrote:Damn that is one enormous slide valve!


That's what she said.
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Re: Semi-auto Vortex Cannon!

Unread postAuthor: jrrdw » Sat Mar 29, 2014 3:19 pm

shiddymunkie wrote:
jackssmirkingrevenge wrote:Damn that is one enormous slide valve!


That's what she said.


And then she pointed her finger, laughed and ask....Are you for real? :oops: :oops: :oops:
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Re: Semi-auto Vortex Cannon!

Unread postAuthor: jackssmirkingrevenge » Sun Mar 30, 2014 6:56 am

Considering a slide valve dumps the firing chamber when the sleeve is pulled back while simultaneously closing off the main chamber, I'd say that's a pretty good analogy :D
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Semi-auto Vortex Cannon! (SUCCESS)

Unread postAuthor: shiddymunkie » Mon Mar 31, 2014 10:47 pm

The cone arrived today, a few days before I expected it to (kudos shapeways):

Image
Image


You may have also noticed that the chamber looks...well, different. That's because I replaced the 7.5ml chamber with a 0ml chamber, as in, it's a plug I used to cap off the QEV.

Image

But why oh why would I do this? Efficiency (important in a semi-auto). I quickly discovered that the air space in the QEV itself was sufficient to create and launch a vortex from this cone, as this video will demonstrate.

While I think I can tweak the setup to be more powerful, yet still be highly efficient, my tests so far seem to imply that the name of the game is most definitely high-pressure/low-volume. In fact, I'm starting to believe that you only need as much air as is contained in the toroid/vortex itself, with anything more than that being excess. As such, I hypothesize that the most optimal volume-to-pressure ratio for a vortex gun is the volume of the toroid at atmospheric pressure, compressed to the maximum PSI your rig can handle. The good thing about this is, the higher the PSI, the smaller the chamber can be AND the stronger the vortex will be. I was limited to ~140 PSI by the QEV (my manual pump only goes up to 160 PSI anyway) but you saw how well that was working. A full 5-link chamber at 140 PSI produced no vortex on the first shot. It did produce a vortex on the second shot however, but the impact of that one looked on par with the impact from a second shot from a 0-link chamber.

More experimentation to come!
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Re: Semi-auto Vortex Cannon! (SUCCESS)

Unread postAuthor: POLAND_SPUD » Tue Apr 01, 2014 6:49 am

Nice
Now just get a fridge compressor and use 500 psi on this

also experiment with chamber size
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Re: Semi-auto Vortex Cannon! (SUCCESS)

Unread postAuthor: jackssmirkingrevenge » Tue Apr 01, 2014 7:09 am

FUS RO DAH!!!

We are very very happy for your success. We are throwing a party in honor of your tremendous success.

Nice one!

shiddymunkie wrote:While I think I can tweak the setup to be more powerful, yet still be highly efficient, my tests so far seem to imply that the name of the game is most definitely high-pressure/low-volume.


Oh yes. In that regard:

Image wrote:Now just get a fridge compressor and use 500 psi on this


This is good advice to follow.

Also, is it possible to generate some smoke to actually see the vortex?
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Re: Semi-auto Vortex Cannon! (SUCCESS)

Unread postAuthor: POLAND_SPUD » Tue Apr 01, 2014 2:15 pm

Cool project BTW
Any ideas how to replicate the cone in the simplest possible way??
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Re: Semi-auto Vortex Cannon! (SUCCESS)

Unread postAuthor: shiddymunkie » Tue Apr 01, 2014 5:26 pm

POLAND_SPUD wrote:Nice
Now just get a fridge compressor and use 500 psi on this
also experiment with chamber size


I am thinking about buying a cheap paintball gun and swapping the barrel out with this cone, as that seems to be one of the cheapest/easiest ways to really ramp up the PSI given the limits of my current setup. I was sort of counting on being able to increase the chamber size to add power, which I'm sure is true to a point, but even a mere ~50ml seemed to be too much air @140 PSI (enough to disrupt the formation of the ring).

jackssmirkingrevenge wrote:Also, is it possible to generate some smoke to actually see the vortex?


I assume it’s somehow possible. Just off the top of my head, I could add an expanded section of PVC between the cone and the QEV that could house some smoke. When fired, the rush of air would surely take some of that smoke with it, thus forming a semi-smoked vortex. But since that setup will ultimately be tailored to the final configuration of the cannon, I think I’m going to hold off for now until I can increase the power. I want "shock and awe" but I’m not sure if I can do that at 140 PSI with such a small cone.

POLAND_SPUD wrote:Cool project BTW
Any ideas how to replicate the cone in the simplest possible way??


Well, the simplest way to replicate the cone is to have one printed by Shapeways like I did. I made the file free for anyone to use, so you can have one printed or even download the file and tweak the dimensions if your into that sort of thing. Here is the link. Here is an alternate link, because I’m not sure which is the one the public can access. The only downside is that it’ll cost you about $80 to be printed out of the same nylon material, aka "white strong plastic".

If you’d like to just make your own, I can give you the specs of the cone and explain a little bit of the reasoning behind why I designed this the way I did. You could then use that info to make your own cone (possibly out of sheet metal, PVC, and epoxy).
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