By now you may be wondering how much air you can launch with a vortex gun, and if you are like me and have a Boom Stick laying around (see Make issue #13), the urge to fire a vortex with the Boom Stick will be irresistible.

You can build a vortex cannon from a concrete pillar mold-form (such as a Sono-tube or Quik-tube, just a giant cardboard tube) and some small sheets of plywood and stiff insulating foam. Foam is easy to use for prototyping but it flexes, losing energy that should go into the vortex. We use foam here as a mounting bracket for the cannon.

The Boom Stick has a 3" FPT exhaust where we will mount the vortex cannon so its barrel is running parallel to the pressure chamber. To do this, you need a mounting adapter.

Weld an MPT adapter into one end of the elbow and the FPT adapter into the other end (using a 3" long section of pipe). Lightly screw this assembly onto the Boom Stick.
Using a length of string and a marker, a washer, and a screw, you can improvise a compass to draw large circles. Mark and cut a plywood ring to hold the MPT fitting in the cardboard barrel.
Glue the MPT fitting into this ring, stabilizing it with duct tape until the glue dries. Glue the MPT assembly into one end of the barrel. Since the cardboard is waxed on the inside, rough up the surface first.
You can also cut a thin ring of foam and glue that into the tube to provide a stronger mounting point. Hold everything together with duct tape until the glue hardens.
Create another ring, between 1" and 3" wide, for the exhaust end of the barrel. Narrower rings are ineffective, and wider rings obstruct the air flow. This exit ring has two purposes; it controls the size (and velocity) of the vortex, and it helps spin the vortex in the first place. Glue the exhaust ring into place.

Delicately test-mount the completed cannon onto the Boom Stick and note the distance between the cardboard barrel and the PVC pressure chamber.
Mark and cut two foam saddles to fit between the cylinders and tape them together along their edges. Tape this bracket onto the pressure chamber.
Carefully screw the cannon onto the Boom Stick mount and tape it into place.
Once everything is stable, set the Boom Stick Vortex Cannon on a table, put on eye and ear protection, attach air and electricity to the Boom Stick, fill the cannon with smoke, and fire it!

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Flaming vortices
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We did some experiments at work with flaming vortices, using an airzooka (a commercial vortex cannon toy). We couldn't find anything that would stay in the vortex and give us a long burn, but propane worked well for a flash of ring-fire. See http://www.youtube.com/watch?v=gFiJo18YYZA
Posted by Dogrocket on September 09, 2008 at 14:11:13 Pacific Time

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