The basic concept is a medium-sized propane burner mounted on top of the hat, with ignition placed about a foot out from the brim. The implementation is somewhat trickier. As I elected to use the readily available 1 pound tanks, there was an issue with the tank cooling down to the gas's melting point, and staying frozen for a very long time. To mitigate this problem, the tank is submerged in an outer vessel filled with warm water, which I've found to cut down the "recharge" time by about 95%, or more depending on ambient temperature. I'd like to emphasize that this is *NOT A FLAMETHROWER*. It does not use a flammable liquid and behaves much like a very large, poorly mixed blowtorch.
The main gas flow originates from a 2 gallon "buffer" tank in series between the liquefied gas tank and the burner. This allows for the projection, for roughly 2 seconds, of a reasonably impressive three metre jet of fire from one's head, even in the temperatures encountered outside my house at this time of year (granted, the water does have to be almost boiling to mitigate the frigid climate at the moment
).The initial plan was to use solenoid valves for all gas flow controls, but due to an issue with an online ordering system, it looks like I'll be doing manual operation of the main gas flow with a 1/4" ball valve mounted in a handle, with 3/8" airline running up and down my arm. The gas flow was deemed too violent for direct ignition from a spark, so a pilot light is being used, which will be ignited by a standard piezo "clicker". Over all, the system will be made more awkward by the all-manual operation, but it should still be tolerable.
Mounting all of this on a round hardhat without damaging the hat was something of a challenge, but two slots on the sides provided just the foothold I needed. 1/8" x 1.25" steel flats are pushed through the slots, bolted on the bottom side to prevent slipping out, bent on top and drilled. The bends and mounting holes in the top plate are done such that the flats are under a good deal of tension, and the top plate is held down very securely on the top. No amount of shaking I can apply to it causes any wobble at all, anywhere.
Included for your enjoyment is a video of the second test, taken in high definition with a Casio EX-FC150. The buffer tank pressure on this shot was only 100psi, but the burner performed very well. At higher pressures (the highest tested so far is 130psi), the hat develops enough thrust to flip itself over backward, but not enough to cause significant discomfort to the wearer.
