Technological flaming sword...

[Johnny1A.2]

A flaming sword (a blade with flames burning around it) is common in fantasy settings using magic. But suppose someone with a lot of brains, access to plenty of money and gear, and a flair for the (melo)dramatic decided he wanted to make a flaming sword in reality. How might he go about such a project?

It would need something combustible, and the only approach that looks even semi-viable to me is some sort of flammable fluid carried along the blade through channels or the like. But the practical issues would be huge.

(Along with using such a device without setting yourself on fire, of course.)

ISTM that somehow heating the blade to high temperatures might be more practical, though then there are issues with melting, softening, etc.

[AlexanderHowl]

Flaming swords are possible, I have seen them in real life (using propane), but they are impractical and dangerous. One reason is that the flame does not follow the sword, meaning that you can catch yourself on fire quite easily. Another reason is that the fuel source is quite vulnerable to damage, meaning that it is almost impossible to safely use it for attack or defense.

Hot swords are easier to make, but they are equally impractical due to blackboard radiation issues. A 500 Celsius sword would probably cause burning damage to its wielder just by proximity. Anyway, firearms are probably better in any situation where you could bring swords.

[whswhs]

Originally Posted by AlexanderHowl

Hot swords are easier to make, but they are equally impractical due to blackboard radiation issues. A 500 Celsius sword would probably cause burning damage to its wielder just by proximity. Anyway, firearms are probably better in any situation where you could bring swords.

A temperature of 773 K just isn't that hot. Its peak emission wavelength is around 3750 nm, assuming that blackbody radiation is a sufficiently close approximation—or about five times that of dull red light. An object heated to that temperature will have a dull red glow; apparently it's comparable to the coals of a wood fire. Blacksmiths work with metal at that temperature all the time, and ancient surgeons used it in cauteries.

[Anthony]

Originally Posted by Johnny1A.2

A flaming sword (a blade with flames burning around it) is common in fantasy settings using magic. But suppose someone with a lot of brains, access to plenty of money and gear, and a flair for the (melo)dramatic decided he wanted to make a flaming sword in reality. How might he go about such a project?

Depends on how long it needs to keep burning. Your basic options are:

• Coat all or part of the blade with something flammable, such as pitch. Easy to implement, won't burn very long.
• Attach something burning to the blade. Somewhat more replaceable.
• Place channels for liquid or gaseous fuel in the blade. Lasts longer than the above, but also more complex to implement.
• Use another means (probably electricity) to produce a fire-like aura.

The main problem with all of them is that a flaming sword is totally useless, it won't help penetrate armor (contact duration is too short and if it won't destroy the blade it's too cool to do ever do anything to metal or ceramic armor) and it will just go out if it penetrates flesh, plus cauterizing the wound isn't really all that valuable.

[Refplace]

Yeah,it would look cool but not be that useful. Though I think more useful than others suggested so far, at least situation-ally.
Against unarmored foes you could set clothing on fire, which is at least intimidating.
But a flaming mace or morningstar would be more practical I think. Look at flaming poi for an example.
I play with fire wands (teaching a class on Saturday in fact) where I use alcohol soaked cotton wrapped in kevlar. I can move it fairly fast without putting t out but the flame is small. You great greater effect with a mix of white gas and lamp oil. Smells worse but burns better, we use that outdoors.
Look at some fire dancing for ideas.
The flame is not so hot it instantly burns the skin, much less damage armor. But it can set clothes on fire, especially if you install a pump that can spay a mist.

[johndallman]

I can see a way to make a more effective weapon, but the person most likely to be hurt by it is the wielder. You use the liquid fuel concept, but rather than using a hydrocarbon fuel, you use a liquid monopropellant which is decomposed by a catalyst plated onto the surface of the weapon.

You have to be quite careful to balance the thrust from the different surfaces of the weapon so it doesn't just take off. It doesn't depend on atmospheric oxygen, so you can develop a lot more heat, and it doesn't go out when you stick it into a target.

But the best way to fight someone with one of these is to stand back and wait for him to have an accident, or run out of his monopropellant.

[malloyd]

Originally Posted by AlexanderHowl

Another reason is that the fuel source is quite vulnerable to damage, meaning that it is almost impossible to safely use it for attack or defense.

And don't forget one of the kinds of damage the fuel system is vulnerable to is overheating. Temperature control of the fuel feed system is a serious issue in rocket design.

And you probably can't set clothes on fire usefully. It's a safety issue for the fire dancing because it can happen some small fraction of the time if you are careless and unlucky, not because it's particularly easy to do if that's what you wanted to happen. It might happen, but I can't see too many weapon purchasers being very satisfied with "it just might work".

Setting anything solid on fire tends to require several seconds of contact with a flame - quite a long time in terms of holding a weapon against something - and cloth doesn't actually burn that well. It's moderately hard to set on fire unless you've either pre-carbonized it or fluffed it up to expose some small fibers. I've had commercial cotton fire-starters go out on me in a light breeze, admittedly they were old enough the hydrocarbon fuel they're normally soaked it had evaporated, but most people don't drench their clothing in kerosene either....

[Sorenant]

It's probably not realistic or practical, but Fallout has the Shishkebab, and Cataclysm: Dark Days Ahead has a few like the Flammenschwert, Rising Sun and Firebrand.

[evileeyore]

Originally Posted by johndallman

But the best way to fight someone with one of these is to stand back and wait for him to have an accident, or run out of his monopropellant.

Sounds exactly like a weapon for a more civilized age.

[Johnny1A.2]

Originally Posted by Anthony

Depends on how long it needs to keep burning. Your basic options are:

• Coat all or part of the blade with something flammable, such as pitch. Easy to implement, won't burn very long.
• Attach something burning to the blade. Somewhat more replaceable.
• Place channels for liquid or gaseous fuel in the blade. Lasts longer than the above, but also more complex to implement.
• Use another means (probably electricity) to produce a fire-like aura.

The main problem with all of them is that a flaming sword is totally useless, it won't help penetrate armor (contact duration is too short and if it won't destroy the blade it's too cool to do ever do anything to metal or ceramic armor) and it will just go out if it penetrates flesh, plus cauterizing the wound isn't really all that valuable.

I agree, it makes very little sense as a practical weapon. But I could I imagine a certain sort of person constructing one.

About the only practical application for it that I can see would be intimidation value, and that only with some people. It would look scary to civilians and amateurs, anyway.,