Butane Wrist Mounted Flamethrower

I'll just start by saying that anyone who is frightened by the idea of myself strapping a container of pressurized flammable gas to my wrist and spewing two foot long flames from my hand should turn back now. Before I proceed any further.

Mom, I'm talking to you.

Ok, now that they are gone, I can get right down to business. 

I made a wrist mounted flamethrower.

If you are now wondering why I would make a wrist mounted flamethrower, it is now your turn to leave my website, before I proceed any further.

Good. 

And for the rest of us, who are impatiently waiting for me to weed out the weirdos and get on to how to how I made this awesome piece of aerosol artillery, I can now move forward.

This is about the simplest way to make a flamethrower there is. Well, scratch that, there are several easier ways to spew flames that I have tried, such as taking a lighter to a can of hairspray, but none, however, that attach to your wrist. This is definitely the easiest and cheapest way to make one of those. I seem to have a thing for easy and cheap projects. Probably because i'm broke, and also,  in the words of Sherlock Holmes, am, "the most incurably lazy fellow that ever stood in shoe leather."

Yeah, I read too much. 

Anyway. 

I did not make a tutorial for you. No step by step instructions telling you exactly what parts to buy and where to put them; but it is so simple that you ought to be able to figure it out without much difficulty. 

But, on to the actual thing. 

The flamethrower is powered by a small canister of butane, which I managed to attach to my arm using a combination of Velcro straps, the case to an old broken monocular, and an old too small archery arm guard. The butane is the smallest size available, the 42g can, which you can buy here
Obviously, you can use a larger can, but the flamethrower won't be as compact.

I then raided the junk drawer for random metal bits, and bought some of the smallest diameter latex tubing I could find. I found a small plastic piece (what it was I have no idea) and used it to connect the tubing to the butane canister. 

"small plastic piece"

I took a little strip of metal, drilled a few holes in it, and mounted that between the tubing and top of the canister; so that when pressed on it would release the gas. I ended up having to reinforce it with some wire, which as you can see I taped to it. It was too thin and was bending when I applied pressure to it otherwise. Then I (with no little difficulty) managed to get some string attached which went down to a loop around my finger; so that when I stretch my hand it pulls on the metal piece which releases the butane. 

After that I bought a (cheap) black glove, cut a hole in the glove, and ran the latex tubing through the hole, attaching it to a bunch of random metal nuts and washers that I glued together, which act as a heat shield. (it also looks cool)

And with that it is finished. Beautifully simple isn't it? I love that the concept can be easily modified to fit whatever materials are on hand. 

This flamethrower can spew fire over two feet, which is quite a lot when coming from your hand.

A few things to know if you make your own:

Aerosol Can

Butane is a gas. Like most gases on this blue marble of ours, it also has a liquid state. The butane is stored in the container under pressure in its liquid form. As the gas is let out, the pressure in the container drops, and so does the temperature. As the pressure drops, the liquid butane begins turning to gas, until it has expanded enough that the pressure is restored. That is how these type of pressurized aerosol products work. It is the same for hairspray, CO2, cooking spray, spray paint, propane, etc. Now, these butane canisters are designed to be turned upside down and, with the nozzle inserted into a lighter's fuel tank, transfer some of the liquid butane into the lighter; where it works with the same principle described above. With making this flamethrower, we are hacking what it's designed to do to fit our own purposes. Because of the way its designed, often some of the liquid butane will make its way into the tubing, and, because of its low temperature, freeze the tubing, which in turn will freeze your arm. (uncomfortable) The liquid butane in the tubing will also continue turning into gas, which can keep the flamethrower going even after you have stopped pulling on the string. For this reason it is best not to keep up a continuous flame for more than a few seconds. Stop and let everything warm up again. Check periodically that everything is still connected securely. You don't want the tubing coming loose from anything, or you may get a fireball within rather uncomfortable parameters to your person. Be sure there are no leaks where the tubing connects to the butane can, or on the opposite side by your glove. Since I used a rubber/plastic material glove, I have to make sure it doesn't get too hot, or let the flame touch it for too long. Not a very good idea on my part, I should have used leather or another more fire retardant material.

I reckon I should also mention that Butane is dangerous to breath in. On the can it says, "excessive inhalation can be fatal".  So......yeah. Don't inhale it.

Be Warned: This is not safe. It is dangerous to shoot fire from your hand. (duh!!) There is always the chance for something to go wrong, and with flamethrowers, if something goes wrong you are generally going to get burned. So be careful!!!

Some people might be wondering what keeps the flame from traveling back into the tubing and blowing up the butane canister, effectually turning the whole apparatus into a grenade. Those people don't understand what fire is or how fire works. The chemical reaction known as fire needs three things to sustain itself: fuel, oxygen, and heat. If it lacks any of those three things, the fire goes out. In this case, butane is the fuel, the oxygen is in the air, and the heat is added when I light the flamethrower. Here's the thing; butane is not flammable. Butane by itself will not burn. Neither will gasoline, for that matter. It is only in the presence of oxygen that they will burn. The flame cannot travel back into the tubing because there is no oxygen in the tubing, only butane. It cannot travel back into the can for the same reason. 

This is a key principle to understand when making flamethrowers. 

Danger alert!!! 

Safety Rant Ahead:

I have received some concern recently as to the safety precautions (or the lack thereof) that I take. I might as well address that here. 

First of all, I consider myself a fairly safe guy. Despite what some of y'all might think, I do not attempt projects that put myself at high risk. Trust me, I don't want to blow myself up. I make it a point to never start on a project until I thoroughly understand it. I must know exactly how it works and why. I know how this flamethrower works. I know why it works. I know the dangers involved, I know how to use it safely, and how to not use it safely. I suggest that you also do not attempt building any of my projects until you thoroughly understand them either. It prevents errors and painful mistakes. 

Secondly, I am not going to put on safety gear when it is not necessary. I am NOT the Crazy Russian Hacker. I WILL NOT put on safety glasses and say "Safety is number one priority" to go hard boil some eggs. Why? For one, safety isn't my number one priority. If safety was my number one priority I would be laying in bed wearing a bubble wrap suit in a concrete bunker 20 feet underground using only kid scissors and never taking a bath ('cause you can drown in only 2" of water) for the rest of my life. Life is dangerous. Every time you get in car you have an enormous chance of being seriously injured or killed. Yet we do so everyday. I take safety precautions only when they are necessary. Putting on safety glasses to shoot a potato cannon is like putting on a chain mail suit to chop carrots. 

Is there slight risk involved? Yeah. Is it necessary to put on safety gear? No.

Thirdly, I do put on safety gear when it is necessary to keep me safe, or when I am dealing with the unknown. I wear welding gloves when I am blacksmithing (most smiths would laugh, but who gets burned more?) I wore welding gloves and a face shield the first time I fired my Football Mortar. I don't stand too close when I light off gasoline. I wear eye protection when I play airsoft. I wear a mask when I'm grinding metal. I could go on, but you get my point.

In this project, you will notice I am not wearing any safety gear. Why? Because it ain't necessary. There is no loud noise - I don't need ear protection. Safety glasses? What for? To protect my eyes from........flames blowing in my face? Are you kidding me? By pointing the flamethrower away from my face, my eyes are not in danger, and it is not necessary for me to wear safety glasses. 

How about a bubble wrap suit people??? I mean, come on! People think I should wear a complete safety getup for shooting my football mortar. Just in case in the realm of ridiculously minuscule distant  possibility that "something" should go wrong. In fact, I should really be wearing a full on crash helmet and suit of armor when walking across our land. Because you never know when a tree might just fall on you. 

But that ^^ sounds silly. You're right. It is silly. Just as silly as me wearing safety glasses to shoot my spud gun. 

It all depends on how people perceive danger. 

Now about my glove...... well, here you might have a point. It would be best for me to have a leather glove for this, instead of a plastic/rubber/synthetic one. With a leather glove, there would be zero chance of my hand catching fire. But I was feeling cheap and bought a synthetic glove. There is a slightly higher chance of my hand catching fire. But, I tested the glove by trying to catch it on fire before I made this. Guess what? It wouldn't catch fire. It only began melting eventually after very long contact with flame. Does that make this dangerous? 

No. The glove is made of thin material, and is right on my skin. I can feel how hot the glove is. If it gets too warm, I instantly blow out the flame. I only keep the flame on for a few seconds at a time for this reason anyway. I recommend having a leather glove, as it is better. Safer by a few points. But I am not in any danger. 

Anyway.

Football Mortar

I'm too tired of typing to put together much of an introduction to this one, so I'll just get right to the point.

I built a Football Mortar.

You know what that is, right? A Mortar? That shoots Footballs? No, not mortar like bricks and mortar, like military mortar. Heavy artillery mortar. Army man mortar. You still don't know what I'm talking about, do you? (sigh) I'll have to explain.

A Mortar is a piece of military artillery which fires a projectile (usually an explosive charge) at a very high trajectory for shorter distances. For going over walls and the like. In comparison, a cannon fires a projectile for longer distances at a low trajectory, for bombarding walls and such. 

And a howitzer fires its charge at a trajectory between the two. Just a bonus fact. (no charge)

I made one that shoots footballs. Talk about a fun opening kickoff! 

This is actually a rather simple project, it only took me an hour or so to complete, and in my usual style is constructed completely out of trash. The only thing you need is duct tape. Lots of duct tape. And lighter fluid. Lots of lighter fluid. And a lighter. A long lighter. Or better yet, a propane torch. And several old empty paint cans. Or giant soup cans. Or giant bean cans. Or giant chili cans. Or--well, you get the idea. Something big enough to fit a football. Actually, the paint cans were a tad too big for the football, which is why I wrapped tape around it, to make it fit snugly. 

You can get a pretty good idea of the construction of the mortar by looking at my drawing of it below. As you can see, the mortar is made of four paint cans duct taped together, making four sections, the top two being the barrel. There is a baffle between both the first and second sections, and the second and third sections; which create the combustion chamber, and are the key to the mortar's success. The baffles are made out of the paint can's lids, with holes punched in a circular pattern around them. At the bottom of the first section, there is a hole punched in the paint can, which is the touchhole and the place where the fuel is loaded. And of course, I couldn't resist stenciling DANGER on it in giant orange letters. 

To fire the mortar I first slide the football down the barrel, ensuring that it fits tightly so as little gas escapes as possible. I then squirt a liberal amount of lighter fluid into the combustion chamber through the touchhole, and then shake the mortar around, turning it this way and that, up and down, spinning it around, etc. The point is to vaporize the lighter fluid and spread it through both chambers. It is rather difficult to get the right combinination of fuel to air in the chamber, so my shots vary in power. When I feel confident that I have gotten the fuel vaporized enough and spread throughout the chamber evenly, (or when my arms get too tired to shake it anymore) I prop it up at a sharp angle, cover my ears and apply the flame to the touchhole. 

Boom!!! 

There follows a deafening bang, and the mortar is thrown back several feet. I quickly look up into the sky, to see the football sailing high through the air, to land nearly three hundred feet away.

Pure dangerous awesomeness!!!!

Now, be forewarned; this is not a risk free project. There are no guarantees that the paint cans or duct tape won't blow apart under the sudden intense pressure. It happened to me once. I didn't wrap enough duct tape around it, and a couple of the sections came apart. 

Flames blow out the touchhole when fired, so be sure and use a long lighter. I watched a vid on YouTube once where some guy tried to light one of these with one of those tiny Bic lighters. He burnt his hand. Bad. Use common sense. A football fired from one of these could probably kill someone if it hit them right.

The combustion chamber will also get hot to touch after repeated firings. 

Did I mention the thing is ridiculously loud?

Some tips for shooting:

Remember that the ratio of fuel to air in the chamber is what determines the success of each shot. Because you can't really measure the amount of lighter fluid you put in each time, it is extremely difficult to get it right. Add to that the fact that the lighter fluid vaporizes differently in different temperatures, and that the oxygen levels in the chamber change after each shot, make getting it right guesswork. You may need to blow out the chamber to get replenish the oxygen supply. I still haven't figured it out. Sometimes I shoot it and the ball only goes twenty feet, and then the next shot goes three hundred. Sometimes I can shoot it twice on one charge, the leftover fuel in the chamber providing enough for the next shot. It's confusing. 

Because the lighter fluid vaporizes differently at different temperatures, you may have to fire it a few times and get the chamber heated up a little before it vaporizes well enough to get a very powerful shot. The hotter it is, the better the naphtha will vaporize.

It is also key to keep in mind that putting more fuel in does not necessarily mean that it will shoot farther. It is the ratio of fuel to oxygen that matters. If there is too much fuel and not enough oxygen to oxidize it all, you get a less vigorous burn. If there is not enough fuel and too much oxygen, you also get a less vigorous burn. It needs to be the correct ratio; and that is difficult get right.

Hairspray Rifle

Yes, you read that correctly, a hairspray rifle. No, it isn't a gun that shoots cans of hairspray (although that would be cool too), rather, it is a combustion powered rifle that uses suddenly ignited hairspray in an enclosed chamber to create high pressures which fire a projectile. Maybe you have heard of a potato cannon. If so, than you will understand it better as simply a small version of that awesome piece of artillery. For the rest of you, I will have to go into a bit more detail.


The gun consists of a combustion chamber made of 1&1/2" PVC with a screw cap fitting on the end. The combustion chamber is then connected to the barrel by several fittings of 1/2" PVC out of the other end. I took apart a long barbecue lighter, and salvaged the sparker assembly. I cut down the wires, and epoxied them into a hole in the combustion chamber. The other end of the sparker assembly becomes my trigger. To fire the gun, a projectile is placed in the barrel. Then I unscrew the cap on the combustion chamber, spray a small amount of hairspray into it, and then put the cap back on. When I push the button on the igniter, it makes a spark in the combustion chamber, igniting the hairspray. The quickly expanding gas created by the ignited hairspray pushes the projectile out the barrel at very high speeds. It is not nearly as powerful as my Pneumatic Rifle, but can still do plenty of damage. The boom/whoosh sound as the gun goes off adds a cool effect that is lacking in the comparatively quiet air rifle. I rigged it to attach to my blowgun as well. (it sends the darts through plywood) Because it is way more powerful than my blowgun by itself, it would be great for hunting small game, although I would need to built it differently to make it more accurate. PVC pipe is too flexible for very accurate shooting, and there is no place on this version to mount a scope or such.

This version is still plenty fun though!

Ignition wires

Trigger sparker