The weapons of Warhammer 40,000 (Part 2).
| << Interrupted service | TBC >> |
Hi and Happy Thursday. Thanks for bearing with my interrupted service last week. This week I’m sticking with the theme of Warhammer 40,000 (40K) this week, focusing (as the title above suggests) on chainswords. These are apparently the standard melee weapon in the 41st millennium for humans and aliens alike (click on images for links):
A chainsword is exactly what is sounds like: a sword which functions like a chainsaw, with a rotating set of toothed blades. If, at this point, you’re completely lost and don’t know what Warhammer is, then I’d suggest going back to last week’s post first because I gave a very brief overview of the game and the lore.
In short, some of the weapons are a bit over-the-top, but that’s completely okay, because 40k as a concept is completely over the top in a grim, dark future in which there is only war. This, after all, is the good guy:
The chainsword stands apart for being especially impractical, ridiculous, and cool. So much so that I felt it deserved its own article. I’m going to spend the following ~2,000 words ripping on the concept, but that’s only because I’m safe in my own house and not out there on the fringes of the galaxy, ripping through a Tyranid swarm with my very own chainsword. In short, I’m jealous, and pedantry is my only recourse.
I’ll start off by talking about power and torque and why there’s no way that anyone—well, maybe apart from the Astartes—who could actually wield the thing in a useful way.
Then I’ll discuss the threat that a proper-functioning chainsword would pose to the person using it. I’ll go into some of the hand-wavey science fiction which is sometimes used to justify weapons like this, before giving my Military Realism verdict on the weapon.
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1. Power and torque pose problems
Chainsaws are not known for being light and agile power tools. There’s no reason a chainsword should be any different.
Let’s talk about the power requirements first. Spinning up a chain of cutting teeth takes a lot of power. For a 3rd millennium chainsaw, this might weigh anything from 3 kg to 9 kg. Electric chainsaws are on the lighter end of the scale, gasoline powered ones on the heavier end.
And guess which type is used by humans of the 41st millennium? It’s the latter. Tanks have big belching diesel promethium engines, and chainswords are powered by miniature versions of the same.
Okay, let’s say you handwave the need for a big engine by saying it’s powered by some unknown, alien, lightweight but energy-dense battery. Or perhaps it uses nuclear fuel or some other exotic material. Obviously, this doesn’t let humans such as Space Marines and Imperial Guard off the hook. Or Orks, for that matter. It is, however, plausible for the Eldar chainsword warriors.
The problem is that even with a light power source, you still have a chain of somewhat heavy teeth spinning around very fast. Chains and teeth are heavy, for one thing, but they also exert a torque as they spin.
The moving mass of the chains and teeth will try to rotate the entire sword in the user’s hand. The fact that the blade (or “bar,” in chainsaw terminology) is long means that this torque is magnified. Remember, torque is force times distance.
It would take a strong grip to hold that rotating mass steady. Again, this might be something that Space Marines can do without breaking a sweat, but un-augmented humans?
Apparently it’s so not a problem for commissars that they can wield a large handgun as well as a heavy chainsword.
Ah, yes, the pistol: that famously accurate weapon, especially with one-handed use. Combine it with a chainsword so you can do two things very badly.
If weights on the order of 3 to 9 kg don’t seem like a lot, then I’d ask you to do a quick experiment. Take a metre (yard) long section of scaffolding pole1 and hold it vertically. Then hold it up at an angle of 45 degrees. Then hold it out horizontally.
How hard was that? Now imagine that it’s sporting a rotating chain and trying to twist your wrist in a certain direction.
Sure, the Astartes (Space Marines) could conceivably do this without breaking a sweat, but for lesser mortals this would not be possible.
And even if it was, would you want to wield a chainsword? It would pose a far greater threat to you than you to any enemy. Let’s discuss that next.
2. The user is in more danger than the enemy
There are more than a few similarities between the chainswords in 40k and Star Wars‘s lightsabers. I wrote an article about lightsabers a few years ago where I pointed out, in my killjoy way, that a weapon like that would be more threatening to the user than to any enemy. Surprise surprise, the same is true of chainswords.
Let’s get one critique out of the way, because it’s such an open goal. Melee weapons have very limited utility in a world of cheap and accurate ranged weapons. The universe of 40k, for all its obvious flaws, still has quite a few highly effective ranged weapons to choose from. Don’t bring a knife (or even a sword, or even a chainsword) to a gun fight:
That critique aside, let’s examine some of the practical effects of using a chainsword in a melee-heavy engagement. The first comes down to fighting technique. You shouldn’t use this like you would a normal sword.
You don’t swing a chainsaw like an axe: the whole point of the buzzing rotary teeth is that they do the kinetic energy bit for you. By the same token, there’s no point in swinging a chainsword in big wide arcs, because it’s adding nothing to the damage of the blow while leaving you open to a counterthrust. Again, this is just like the lightsaber. Someone tell this berserker Space Marine that he’s wasting his energy:
If you ever watch videos of lumberjacks felling or slicing trees2, pay attention to how much control they exert over the blade. There’s very good reason for this. A phenomenon called “kickback” has the gruesome potential to bring the saw blade up and into your face if it’s not controlled properly.
Whereas you can educate a sawyer to not use the tip of the saw, it’s much harder to enforce this kind of practice in the heat of combat, with an enemy who’s trying to kill you while also avoiding being chopped up by his own sword.
Even if you can avoid kickback, you still need to worry about any part of the blade coming into contact with your limbs, armour, trailing bits of cloak or scroll, or buddies.
Not to mention the bits of enemy and the teeth of the sword itself which will become dislodged through wear and tear until they’re launched at high speeds right into your face.
At this point you might be tempted to bring in some science fiction handwaving and talk about monomolecular blade edges. These solve some of the problems I’ve discussed above, but only at the cost of bringing in far, far more. Let’s discuss them next.
3. Monomolecular cutting teeth solve some problems, bring many more
Some sources3 try to explain away the practical problems of chainswords by talking about their “monomolecular” cutting edges.
This usually doesn’t apply to the bog-standard human versions, but rather to the xeno versions or, if human, the fancier (i.e. Space Marine) ones.
A monomolecular blade is, as the name suggests, a blade that’s so sharp that its edge is only one molecule thick. That’s quite sharp! For context, the sharpest edge we 3rd millennium humans have managed is about 3 nanometers, which is about 24 (iron) atoms thick.
Not quite there, but not a million miles off, I hear you say. But there’s a problem. Assume you could sharpen a steel edge to be a single atom thick. The resulting material, at least on that edge, wouldn’t be steel anymore. Steel is a mass of jumbled-up crystals of iron and carbon. Without the carbon it’s just pure iron, which is very soft: not a suitable blade material.
You couldn’t sharpen a steel blade to be this thin, because the material would chip and break and separate at the level of boundaries between these crystals (called “grains” in steel).
So steel is out: sorry Imperial Guard, Orks, and other users of chainswords who are lower down the tech tree. What about exotic super-materials in the lore? Things like diamantine or adamantium?
The problem here is that materials science is unforgiving. Swords need to balance two demands. They need to be hard and they need to be tough. What’s the difference? I thought you’d never ask.
- A hard material like diamond, glass, tungsten carbide, or some steels resists deformation. Hard materials are great for cutting other, softer materials.
- A tough material like aluminium, polycarbonate, or some steels absorbs energy without fracturing. Tough materials are great for structural uses.
Some steels are harder, some are softer, some are tougher, some are more brittle, but most of them strike a decent compromise between the two. It’s why steels are so popular. A steel sword needs to be both hard and tough. Sometimes this is accomplished by getting a compromise recipe throughout the blade, other times with fancy dual-material blades where the tough but softer material is in the core, with the edge made from harder, more brittle material.
The point of this aside is just to say that there’s no magic material which is perfectly strong and tough, so the idea of making a monomolecular blade for sword fighting is far-fetched.
If we did manage to make a monomolecular blade (or tooth in a chainsword), then the resulting weapon would be even more of a liability to the user. It would also completely obviate the need for a rotating chain mechanism.
But it would make a cool weapon even cooler. And, at the end of the day, isn’t that the whole point?
Conclusion: The triumph of the cool
Space Marines are famously clad in ceramite “power” armour which stops most attacks and interfaces with their body to enhance their movements. Terminator armour is heavier still and with even greater integration with the superman within.
Total coverage with super or über-super armour is one of the defining characteristics of Space Marines.
Except when it’s not.
If you didn’t spot the glaring omission from the squad above, it’s the helmet on the squad leader. You know, the single most important piece of armour which protects the most important part of the Marine.
Soldiers not wearing helmets is ridiculous, but we give these guys a pass because it looks cool as hell.
Chainswords are the same. Utterly impractical, impossible to wield, and presenting more danger to the user, they are not a good weapon. There’s no way that that changes in the next 38,000 years either. Really, I’ll wait just to be proven right.
Be that as it may, they are hella cool. And, with Warhammer 40,000 (as with most good science fiction), isn’t that the most important thing?
What do you think? Let me know in the comments below. As always, remember to subscribe if you haven’t already. Thanks again for reading.
Cover picture: Warhammer 40k: Space Marine 2 Wallpaper #5, by ChristianP7676 on Deviant Art (2025)
- Please don’t actually do this, unless you happen to have scaffolding poles lying around your house, or you work on a site. Whatever you do, don’t go taking apart some scaffolding just because some guy on the internet told you to. ↩︎
- I don’t know what you do for fun, and I don’t judge. ↩︎
- Which is a fancy way to describe a bunch of open-source fan-generated lore. ↩︎
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