Flamethrower V1 - 2015
So this first started as a 10th grader’s dream after watching Iron Man for the 8th time. Sure you could put a lighter in front of a deodorant can and shoot a flame (DON’T TRY THAT AT HOME), but I wanted something more robust, wearable, and hopefully, safe.
This entire documentation should a have DON’T TRY THIS AT HOME disclaimer, so here it is.
This was my first build from 10th grade. It wasn’t safe by any means, and I was extremely naive in terms of the amount of factors I had to think of (gas pressure, material melting points, etc.) All I really knew was: spark + butane = flame! I won’t be going over the details of this build, because no one in their right mind should try and construct this version of the flamethrower.
Flamethrower V2 - 2018
Here’s build number 2. It’s a little better and took a few years of me getting into university to sit on the design enough before thinking I could get at it again. The build is a little more robust, with a metal frame under the resin-hardened cover material.
I got a bit better at understanding circuits, so I modified the spark generator out of an Electric Fly Swatting tennis racket. As shown below, the circuit is housed above the butane cannister housing, and runs 4 wires to the palm. 2 for the actual spark, and 2 for the button to initiate the spark.
The butane cannister housing is completely modular and allows you to swap out entire butane cannisters when needed. The palm is hooked to a crude mechanical linear actuator on a drawer slider to press the butane nozzle the more the wrist is raised back. Thus allowing a rough variable butane flow.
This design more or less satisfied my desire of my Iron Man-esque flamethrower, but after revisiting this project after so many years, I had so many ideas on how I could make it better, stronger, and importantly, smaller.
Flamethrower V3 - 2019
Haha yes I know, it looks like a Spider-man web shooter. It wasn’t my complete intention but sort of stumbled on the design coincidentally halfway through designing the entire enclosure.
So I figured I could modify some lighter cartridges to remove their fuel regulators and increase their nozzle lever range. The 3D File is attached to this page if you want to give it a shot.
This model makes use of an actual spark generator I picked up on Amazon for like $6, a LiPo battery and charger, and the refillable lighter cartridges.
So here’s some science:
Butane is extremely flammable as a gas, but not as a liquid. The butane in lighters are only in liquid form, because of the internal pressure of the lighter, which is around 25 psi. A flame requires 3 things: oxygen, heat, and an oxidizing agent. There’s no oxygen in the lighter cartridge, otherwise the butane wouldn’t be a liquid. Using the mini butane redirection pipe, the flamethrower’s flame can’t enter back into the lighter. So the only cause of concern is the overall temperature of the lighters, not by the flame but the overall environment temperature. At 180 degrees Celsius, the internal pressure of the lighter increases to around 200 psi, this is since temperature and pressure have a direct relationship (PV = nRT). So given my precautions, we shouldn’t be at risk of our lighters exploding on our wrists. But even so, it’s just good practice to be as safe as possible.
The butane outflow nozzles are directed at slight elevated angle from my wrist, and from the picture you can see the variable butane release lever that extends to my palm and houses the spark button. The more I pull the lever down (away from the nozzle) the more butane released, and the butane release stops when I bring my wrist back up to steady state.
Ok I didn’t install the butane channel for this video, promise I’ll upload an updated one.
This is probably my best design yet, and while I don’t intend to work on it in the near future, this flamethrower project isn’t something I’ll probably ever give up. I’m already thinking of future plans with hydrogen generators, but more on that later.
Thanks for reading and checking out my 5 year long flamethrower project.