Watch as Youtuber The Backyard Scientist experiments with the world’s biggest vortex cannon, the VRAD! While most vortex cannons we see online and in real life use rubber bands, this one uses explosions. On one end, it has a 28-inch barrel, and at the other, a gas tank that they fill with a mixture of oxygen and other gases in just the right ratio to get the perfect explosive mixture that will propel the vortex ring with astonishing force through the barrel.