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LAN_403

HV Enthusiast

Thu Aug 24 2006, 01:29AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Well, its official. I showed the guy in charge of demonstrations for the Family Day event at my company and he wants a Vortex cannon for the kids. So guess who has to build one. Good thing I get to do this on company time!

Anyways, I plan on using a large plastic garbage can and probably purchase an cheap commercial fog machine.

Just a couple of questions:

1. Is there any tricks on properly sizing the exit hole for this cannon, or is it pretty much trial and error or not that important?

2. Also, i'll probably get a rubber sheet from McMaster-Carr. Any ideas on what would be a good rubber compound to use for the end membrane???

Thanks in advance!

Superkuh

Thu Aug 24 2006, 04:37AM

Registered Member #59 Joined: Thu Feb 09 2006, 05:45AM
Location: Wisconsin, USA
Posts: 12

I have collected a few documents on higher energy vortex cannons that you may be interested in at:
http://nervousenergy.net/vortex/

[MODERATOR EDIT: Company Proprietary information is not permitted to be posted on the website.]

[Superkuh EDIT: Government Information. Approved for public release, distribution unlimited.]

I found the above removed document on a public database (STINET DTIC), and it seems to be funded with public resources. I appreciate your efforts to maintain the forums integrity, though.

STINET DTIC wrote ...
Accession Number:
ADA372518

Full Text (pdf) Availability:
Size: 3 MB
Handle / proxy Url:

Citation Status:
ACTIVE

Title:
Vortex Ring Generator: Mechanical Engineering Design for 100-kpsi Operating Pressures

Fields and Groups :
200400 - FLUID MECHANICS
Corporate Author:
ARMY RESEARCH LAB ADELPHI MD

Personal Author(s):
Lucey, George K., Jr

Report Date:
JAN 2000

Media Count:
52 Pages(s)

Organization Type:
A - ARMY

Report Number(s):
ARL-TR-2096 (ARLTR2096)
XAARL/ADELPHI (XAARLADELPHI)

DescriptiveNote:
Final rept.

Monitor Acronym(s):
XA (XA)

Monitor Series:
ARL/ADELPHI (ARLADELPHI)

Descriptors:
*VORTICES, TECHNOLOGY TRANSFER, SAFETY, MECHANICAL ENGINEERING, MACH NUMBER, STATIC PRESSURE, GAS GENERATING SYSTEMS, EXPLOSIVE GASES, VORTEX GENERATORS, JET STREAMS, SUBSONIC NOZZLES, NONLETHAL WEAPONS.

Identifiers:
EXPLOSIVE GAS GENERATOR, VORTEX RING GENERATORS, CROWD CONTROL, PE62120A

Abstract:
This report documents engineering design guidelines used to construct an explosive gas generator (100 kpsi maximum) and an adjustable area ratio (2844 maximum) nozzle. The equipment enables ring vortices to be generated using jet streams with significantly higher Mach numbers than previously reported in the literature. Studies are planned of the risks, limits, and capabilities of ring vortices for nonlethal crowd control applications. The focus is limited to 40-mm weapons, so this report is written to facilitate technology transfer to investigators interested in other applications and launch platforms.

Distribution Limitation(s):
01 - APPROVED FOR PUBLIC RELEASE

Source Code:
424778

Document Location:
DTIC

Geopolitical Code:
2405

Citation Created:
02 FEB 2000

Citation Updated:
18 JUN 2003

Tesladownunder

Thu Aug 24 2006, 05:50AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

Now a veteran of many hundreds of shots mine has been going fine. You don't need a fancy elastic membrane. I used a rubberised picnic blanket which is strong, flexible and airtight and cheap. If you stick a round doorknob into it and fasten it with a plastic tie you dont even have to put a hole in it. This leaves the inside to attach an elastic strap to. Even that is not essential as you can push it in and out manually rather than relying on recoil.
Just a caution on the garbage can. You need to get the smoke in from the smoke generator. If your whole unit is small you can't put it inside and you will need some form of tubing to connect. They are not designed for this and there will be heat and condensation issues.
The smoke generator has a warning not to operate it more than 15 degrees from the vertical. I have blown one for some reason ? pump failure.
The way mine sits the smoke will be directed in a circular manner around the inside of the vortex generator. This I think tends to keep the smoke in and perhaps closer to the edge rather than the center.
A sturdy frame is good preferably aimable and a gun sight on the top will be my next addition.

I used a 50 % hole. A larger hole means bigger rings but more open to the air and smoke loss and fewer shots before refiring the smoke generator.
Note that wind tends to ruin the effect so a sheltered area in sunlight would be best.
Indoors runs the risk of triggering smoke detectors.

Peter

Bjørn

Thu Aug 24 2006, 05:59AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

I have used holes smaller than 30% with quite a lot of pressure to deliver more punch, so the size of the hole is not critical. I would have made a large hole in the garbage can and some plates with different size holes to study the effect.

HV Enthusiast

Thu Aug 24 2006, 11:52AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

Thanks for the info.

So you are saying that I won't be able to put the smoke machine inside the garbage can?
Thanks

Dan

Tesladownunder

Fri Aug 25 2006, 01:12AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

I don't think you will fit my type of smoke generator in a garbage can without it filling a lot of the space and possibly affecting the flow of air adversely. My generator measures 32x15x15 cm with the outflow at one end so would need some clearance otherwise you will be blowing hot air onto plastic. You might just need to stick it in from the side or try a short corrugated tubing connection with aircon ducting or swimmng pool hose.

Superkuh wrote ...

I have collected a few documents on higher energy vortex cannons that you may be interested in at:
http://nervousenergy.net/vortex/

Blowing over a mannequin is a lot easier than blowing over a real person.

Peter

1156468327 10 FT15085 Vortexbigfogmachine

Nik

Fri Aug 25 2006, 05:19AM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

I ended up setteling on a 50% diameter hole in my cannon and it has been fine. I based my cannon off of these plans

. I am using a thick plastic bag as a as a diaphram. There is wood clamping together on oposit sides of the plastic (in the center) with an eye-bolt on each side. One as a handle to draw in air, the other is for the bungee cord.

HV Enthusiast

Fri Aug 25 2006, 11:09AM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

TesladownUnder,

I assume you have the center of your tablecloth diaphram connected to a bungee type cord which is then attached to the front of the barrel??

Thanks
Dan

Nik

Fri Aug 25 2006, 05:25PM

Registered Member #53 Joined: Thu Feb 09 2006, 04:31AM
Location: Ontario, Canada
Posts: 638

I cant tell you about TDU's cannon but i can tell you that the bungee isnt a necesary part. Larger cannons need only a brisk push on the diphram to launch a ring.

Tesladownunder

Sat Aug 26 2006, 01:04AM

Registered Member #10 Joined: Thu Feb 02 2006, 09:45AM
Location: Bunbury, Australia
Posts: 1424

EastVoltResearc wrote ...

I assume you have the center of your tablecloth diaphram connected to a bungee type cord which is then attached to the front of the barrel??

Yep. I have a short cord which allows a full range of movement. With a doubled up length which my son preferred, the rings were much faster but he got blisters after about an hour I reduced it to one length. It is optional and you can simply push the air out slowly but you can still do this with the elastic cord.

Peter

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