Semi-auto Vortex Cannon! (SUCCESS)

[POLAND_SPUD]

Well I was looking for a Diy solution

PB guns don't really run at high pressures... building a fridge compressor isn't very difficult ->

[shiddymunkie]

Well I was looking for a Diy solution

I hear ya. There are many ways you could make this cone -- I don't believe it needs to be super precise in order for it to work. It could be something as simple as rolling up some sheet metal and securing it with rivets or screws. You might even be able to make the cone itself out of something like cardboard, so long as the throat of the nozzle is made of something more robust (like a PVC fitting or metal washer). I'll give it some thought, however, and see if I can cook up a cheap/easy way to make a functioning cone.

PB guns don't really run at high pressures... building a fridge compressor isn't very difficult ->

They don't? I don't really know much about paintball markers, but when I was looking at HPA tanks to adapt to this vortex cannon, I was having trouble finding ones with output pressures of less than 500-800 PSI. Is the air that propels the paintballs less than this output (due to an internal regulator or some such)? And if so, is that pressure adjustable?

I'd like to keep this rig "mobile" if possible.

[POLAND_SPUD]

Sure... HPA tanks are 500-850 psi or so, but pb guns operate at much lower pressures. Mostly to keep muzzle velocity within safe limits

[jackssmirkingrevenge]

Sure... HPA tanks are 500-850 psi or so, but pb guns operate at much lower pressures. Mostly to keep muzzle velocity within safe limits

?

Most paintball guns are designed to run on 800-900 psi, and firing most paintball guns without a barrel is not something you want to subject your ears to. Don't forget that you're not only firing a 3 gram paintball at 300 fps but also cycling a rather heavy action.

You can buy something like the Gryphon and a 48 CI air tank for less than 100 bucks from Walmart. If it doesn't work, you still have the basis for a more destructive semi-auto

[POLAND_SPUD]

Don't forget that air is further regulated in the gun itself

[jackssmirkingrevenge]

Don't forget that air is further regulated in the gun itself

Not really, and having handled more paintball guns in the past 6 months than I have in my entire life I can say this with some certainty There are a few with internal regs, like the BT TM7, but the vast majority have no such system.

Let's take the good ol' 98 Custom as an example:



The bottle is attached to the bottom of the grip, from there the air goes at its full pressure up the braided steel hose directly to the valve.

[POLAND_SPUD]

Tippmann 98 is not a good example as it is a typical HP gun. Electropneumatics use lower pressures. Besides operating pressure isn't the same as breech pressure.

[Anatine Duo]

I think he means the pressure in the chamber is low. Don't most markers use a high-low pressure system? All mine do... with their frustratingly tiny valves. 800 psi would blast a hole through a paintball instantly I thought.

Oh and awesome toroidal vortex launcher btw! Let's see some smoke!

I tried a half-assed cone on my 1322 but no vortex, I think it needs the muzzle choked?

[shiddymunkie]

Anatine Duo ,
See below for a cross-section of the cone:



As you can see, the cone is essentially a nozzle with two main parts. The air that comes out of the QEV is allowed to expand in the larger diameter of the chamber (2x) before being forced through the smaller diameter of the throat (1x). This abrupt transition is what “peels” the air back onto itself, causing the rotational forces that form the toroid/vortex.

All the cone does is help to facilitate the growth of the vortex when dealing with higher air pressures, which is why no cones are needed with the hole-in-a-box style cannons. A high-pressure burst of air can simply be too turbulent for a stable vortex to form (too much air and/or too much energy). The cone helps regulate that excess air/energy so that it’s added to the vortex, instead of allowing it to disrupt the vortex.

The important thing to remember here is that a cone itself does not create a vortex, the chamber and throat do. If you have no chamber, there is no rotational motion to be amplified by the cone. All a cone would do in that instance is perhaps amplify/direct the sounds of the blast. But then again, I’m pretty new to all of this stuff so I could be completely off base [/disclaimer]

[matti]

I think now Larda should make cone for HyGaC20... the cone probably could be done by EDM machining and some stainless steel

[jackssmirkingrevenge]

Tippmann 98 is not a good example as it is a typical HP gun. Electropneumatics use lower pressures. Besides operating pressure isn't the same as breech pressure.

Electropneumatics aren't cheap

[Anatine Duo]

thanks shiddymonkey, that clears a lot up for me, I initially thought your chamber was just a fitting to go over your valve outlet...

I think we will see more of these... in fact every cannon with interchangeable barrel should have one! Better yet the "propellants that shall not be named" can be used... they often come with their own smoke

[shiddymunkie]

Tippmann 98 is not a good example as it is a typical HP gun. Electropneumatics use lower pressures. Besides operating pressure isn't the same as breech pressure.

Electropneumatics aren't cheap

So, is the consensus that entry-level (cheap) paintball markers crank out decent PSI at the breech? Do the markers allow that pressure to be adjusted? Also, what sort of air volume is released per shot (and is that adjustable)?

I think we will see more of these... in fact every cannon with interchangeable barrel should have one! Better yet the "propellants that shall not be named" can be used... they often come with their own smoke

Well, perhaps. I did a little bit of testing today and I'm not sure if someone could simply strap a cone to their existing spudgun and have it work. More testing is needed before I can put forth a worthwhile claim, but my hunch is that some sort of balance between cone size, PSI, and air volume must be struck for everything to work right. As to how how big (or small) that "sweet spot" is, who knows...

Speaking of testing -- does anyone have any ideas on a good way to measure the power of a vortex? I was thinking of testing each chamber size (0, 1, 2, 3, 4, 5, and 6 links) across various PSI levels (60, 80, 100, 120, 140), thus giving me 35 different points of reference to draw conclusions from. The problem is, I need a consistent way to measure/quantify the power of each test fire. At the moment, I'm just eye-balling how violently the trash bag moves when I shoot it from a fixed distance, but that sort of sloppy approximation doesn't tell me much. I need to convert the results into numbers somehow...

[matti]

Speaking of testing -- does anyone have any ideas on a good way to measure the power of a vortex? I was thinking of testing each chamber size (0, 1, 2, 3, 4, 5, and 6 links) across various PSI levels (60, 80, 100, 120, 140), thus giving me 35 different points of reference to draw conclusions from. The problem is, I need a consistent way to measure/quantify the power of each test fire. At the moment, I'm just eye-balling how violently the trash bag moves when I shoot it from a fixed distance, but that sort of sloppy approximation doesn't tell me much. I need to convert the results into numbers somehow...

http://en.wikipedia.org/wiki/Ballistic_pendulum ..and camera.

[shiddymunkie]

http://en.wikipedia.org/wiki/Ballistic_pendulum ..and camera.

Great suggestion! I made a ballistic pendulum (video here) and did some tests. It turns out that my suspicions were on to something. As mentioned before, I tested 7 different chambers sizes (ranging from 0 to 6 "links") across 5 different PSI pressures each (60, 80, 100, 120, and 140) and measured the results on the ballistic pendulum. At first, and contrary to my expectations, it began to look like there was no limit to how much air could be shot through the cannon...the bigger the chamber, the greater the movement on the pendulum.

Since this was a bit of a surprise for me, I began wondering if that movement was the result of a vortex... or if it was possible that movement was being caused by a turbulent plume of air. After all, I was standing just 6 feet away -- and with the cannon itself being 3 or so feet long, the muzzle was only a few feet from the pendulum. I decided to try some distance shots with these higher pressure/ higher volume capacities, and sure enough no actual vortexes were being made. In the end, and after doing far more than the initial 35 tests, I discovered the following:

Max Power by Chamber Size
0-link (the plug) = 7" @ 140 PSI
1-link = 4.5" @ 110 PSI
2-link = 6 1/8" @ 100 PSI
3-link = 5 1/2" @ 80 PSI
4-link = 5 1/2" @ 80 PSI
5-link = 4" @ 70 PSI
6-link = 2 1/2" @ 60 PSI

For all but the 0-link chamber, I was eventually hitting a PSI ceiling. At even 10 PSI over the above levels, vortex formation was hit-and-miss. Those that were formed had wildly unpredictable trajectories and exhibited atypical impact patterns on the plastic trash bag. The vortex rarely hit where I was aiming, even from close distances, and they seemed somewhat weak on impact -- spread over a larger area instead of the small, focused impact of the lower PSI shots of the same chamber size. At 20 PSI over the above levels, vortexes stopped being formed all together.

This has led me to believe that, without modifying the cone itself, the only way to really ramp up the power is to increase PSI and stick with the plug. Otherwise, either the size of the throat opening, the size of the muzzle opening, the length of the cone, or some combination of those things will need to be increased in size to accommodate the extra flow while still allowing vortex formation.