Plausibility Check: Magical Railgun

[SinghSong]

In one of the magical fantasy parallel world I'm working on (for a light novel in the isekai genre), the magic system is essentially tantric in nature, and the most important, widespread and impactful applications of magic are via the use of yantras (literally, "machine/contraption"- i.e, mystical diagrams, patterns and engravings, akin to the western concept of runes, but with the use of colors and special materials also critically important in their composition and effectiveness), and their larger counterparts, mandalas. These traditionally have to be consecrated and mystically energized first, and then enable their users to induce specific magical effects, which are activated and/or supercharged through the use of the proper mantras in tandem, until this mystical energy gets depleted and essentially needs to be recharged once more; with exponentially more powerful yantras/mandalas requiring exponentially higher magical quotients to 'consecrate' (i.e, install), energize and recharge them.

So, for my MC protagonist, rather than going with the tired old cliche of adopting a magically enchanted melee option like a katana as his primary weapon, or taking up archery to use a magically enchanted bow and arrows (which do exist as the primary weapons of war in this setting), I was thinking about having him make the most of his otherworldly knowledge to craft and use what would effectively be a magical railgun instead- using a magazine of kinetic impactor rods as ammunition, a spring-loaded trigger mechanism to give them their initial impetus, and a pair of identical rails with a series of relatively weak, mundane (with low power requirements) yantras engraved into both of them, with each successive pair of yantras magically accelerating the payload by the same exponent each time,(with a later 2nd generation model automatically only activating each successive pair of yantras as the projectile passes down the gap/barrel between them, rather than the wielder needing to activate all of them simultaneously, vastly reducing the already relatively low magical power requirements to use it as a result). So what do you reckon- does it sound both plausible, and novel enough for no-one else in the fantasy parallel world to have come up with the concept first?

 

[joshua mcdermott]

my brother build something similar in DND a long time ago - seems plausible enough and makes sense as an invention for the MC - particularly if they don't know how to use swords/bows etc. Everyone else perhaps grew up with them so would not need to invent something, where the MC may ahve experience with firearms and naturally develop something they can use well.

 

[Eduardo Ficaria]

Regarding the plausibility in general, there's the question of that kind techonology being known within the MC's culture. I mean, does the MC's culture create such elaborate and advanced magical tech? Or is it just something the MC has created after years of studying the tech? What I think wouldn't be believable is that such weapon or similar tech was created out of thin air, without any previous attempts or approximations to the tech, either from within the MC's culture or from neighbouring countries. On a character level, if your MC is more of a magician/engineer it makes sense to him to use weapons like that. I mean, a gun trumps a sword any time. So, if your MC is not a warrior or has no military background, weapons like that magical railgun will suit him better than swords and arrows. Still, the MC would need some proper training to use and move around with it and similar weapons, in a similar way modern soldiers have to go through.

Now, about the technical plausibility of such weapon. Bear in mind that a railgun has huge energy requirements, generates a lot of heat and (as far as I've seen in the real cannons currently being developed in the US) have really long and thick cannons. With those limitations in mind, I would consider the following points:

• Every time you shoot the gun, it'll need some time to cool down. And probably your MC won't be able to force the cool down with magic or water to make it faster. The materials might not take it well and break, or it could also affect the spells engraved into the weapon parts and make them weaker or even imprecise. This is good from a dramatic point of view when building your story.
• Also, in a real railgun the projectiles get shot at extremely high supersonic speeds, creating really hot plasma due to friction with air. Now imagine shooting such a thing in front of your face (or at a rather short distance). How would you protect the user from the flash? I think you could go for an exaggeratedly flared muzzle, taking inspiration from Blunderbusses for instance.
• If the weapon has a magazine, I don't think it will be very big. This means limited rounds per mag, as it happens with real sniper rifles, compared with assault rifles. Of course, this depends on the caliber of the rods your MC is planning to use.
• Weight. If a sniper rifle is already a heavy thing, imagine a railgun. Also, take into account the weight of the ammunition. This means that your MC won't be able to carry much ammunition around.
• If the weapon is completely custom made, this means that no one but the MC is able to fix it when it breaks, or to make the ammunition with the proper specs. Also, think about the rarity of the tools, materials, pieces and spells used to build the weapon: this makes its maintenance a really tricky thing.
• One could say that weapons like these are long range in nature, and shorter or smaller versions of it may or may not get the most of the potential benefits of the basic design. It all goes down on how advanced are in your settings, I think, to be able to apply the science properly at different scales.
• Your description of how the rod would be accelerated through the rails reminds me of a coilgun. I thought you would like to consider this for the design of your MC's weapon.
• Since the realgun can be an unwieldy beast (it's essentially a heavy sniper rifle with magical batteries attached to it), your MC will need other weapons for medium and close combat. Or just some sort of magical protection, at least to be able to stand on its own when required.

To sum up, yes your MC's railgun should be plausible although its not that simple as this huge gunz shoots stuff automagically. Although I'm aware that you're working on a light novel, I think using a bit those little details can help improve your story.

 

[SinghSong]

Regarding the plausibility in general, there's the question of that kind techonology being known within the MC's culture. I mean, does the MC's culture create such elaborate and advanced magical tech? Or is it just something the MC has created after years of studying the tech? What I think wouldn't be believable is that such weapon or similar tech was created out of thin air, without any previous attempts or approximations to the tech, either from within the MC's culture or from neighbouring countries. On a character level, if your MC is more of a magician/engineer it makes sense to him to use weapons like that. I mean, a gun trumps a sword any time. So, if your MC is not a warrior or has no military background, weapons like that magical railgun will suit him better than swords and arrows. Still, the MC would need some proper training to use and move around with it and similar weapons, in a similar way modern soldiers have to go through.

The MC has some basic military training, having been a former cadet and fired a rifle before, but nothing much beyond that (other than action movies, and knowing that guns trump swords). He is indeed more of an engineer/thinker type character than a warrior/fighter character; in the other world, the body he's in (with the 'isekai' having happened via an interdimensional mind-meld, where he wakes up in one of the two worlds whenever he goes to sleep/falls unconscious in the other, with a merged stream of consciousness and both sets of memories) isn't particularly strong, being slightly below average, but with the combined intellects of both his former selves, he is a genius by the standards of both worlds, in both science and technology and in magic.

Now, about the technical plausibility of such weapon. Bear in mind that a railgun has huge energy requirements, generates a lot of heat and (as far as I've seen in the real cannons currently being developed in the US) have really long and thick cannons. With those limitations in mind, I would consider the following points:

• Every time you shoot the gun, it'll need some time to cool down. And probably your MC won't be able to force the cool down with magic or water to make it faster. The materials might not take it well and break, or it could also affect the spells engraved into the weapon parts and make them weaker or even imprecise. This is good from a dramatic point of view when building your story.

Not necessarily, regarding cool-down times- remember, real-world rail-guns (or coil-guns, for that matter) generate a ton of heat, and have huge energy requirements, because they work via electro-magnetic propulsion. For the hypothetical 'magical railgun' weapon, I was imagining individual pairs of yantras (or coils, to use the coil gun analogy) not that much more powerful, insofar as the acceleration imparted by each, than the maximum imparted by a bow shooting an arrow- which can actually be up to 130g's, or 1,300m/s2- and as a result, a similar level of wear and tear, along with heating, centred around each yantra, as you'd get in a longbow after shooting it (albeit concentrated in a far smaller area, and accordingly more wear-intensive as a result- I mentioned a 2nd generation model, since the 1st generation working model's going to fail and/or lose its accuracy fairly quickly). And which, for a system which can apply that level of acceleration continuously for over a meter, would still be enough to propel high-velocity/borderline hypervelocity rounds.

• Also, in a real railgun the projectiles get shot at extremely high supersonic speeds, creating really hot plasma due to friction with air. Now imagine shooting such a thing in front of your face (or at a rather short distance). How would you protect the user from the flash? I think you could go for an exaggeratedly flared muzzle, taking inspiration from Blunderbusses for instance.

At first, for the 1st generation/prototype model, I was contemplating whether or not to even have a barrel at all, let alone a muzzle- with just the two rails needed to propel the projectile, along with some way to keep them equidistant along their length, and some measure of inaccuracy accepted as a given (basically, so long as it's still an improvement on the accuracy of a crossbow bolt, it'd still be 'good enough'), could this potentially reduce the friction, and allow the hot plasma to dissipate more effectively? Or would the backlash be more likely to harm the user? If the latter, then there probably would stuill have to be a barrel, and a flared blunderbuss-style muzzle, or something similar. And of course, it may be worth mentioning that the yantras/runes are effectively all-purpose particle accelerators- as such, if they're accelerating the air enveloping the projectile to the same degree than they're actually accelerating the projectile itself, would air resistance, and the resulting hot plasma generation, actually be an issue within the barrel/between the rails at all? Or would it just result in a flash (and/or sonic boom from accelerating the air alone, even when the magazine's empty, adding a bit of versatility and close-range melee option for the weapon) once it's actually left the barrel?

• If the weapon has a magazine, I don't think it will be very big. This means limited rounds per mag, as it happens with real sniper rifles, compared with assault rifles. Of course, this depends on the caliber of the rods your MC is planning to use.
• Weight. If a sniper rifle is already a heavy thing, imagine a railgun. Also, take into account the weight of the ammunition. This means that your MC won't be able to carry much ammunition around.

It wouldn't have an exceptionally large magazine, but considering that there's no need for propellant, it could still well be markedly larger than an equivalent sniper/anti-material rifle the same size (say, 20-30 rounds, rather than 10-15). Or alternatively, a larger caliber of 'rods from god' could be used, making it more powerful- but of course, that'd also make it increasingly heavy, and limit the amount of ammunition, as well as effectively turning it into a portable artillery piece rather than a handheld weapon (since he'd get knocked off his feet at the very least, or even killed, just from the recoil of the weapon- more so, given that he's slightly below average physically, at least at first)

• If the weapon is completely custom made, this means that no one but the MC is able to fix it when it breaks, or to make the ammunition with the proper specs. Also, think about the rarity of the tools, materials, pieces and spells used to build the weapon: this makes its maintenance a really tricky thing.
• One could say that weapons like these are long range in nature, and shorter or smaller versions of it may or may not get the most of the potential benefits of the basic design. It all goes down on how advanced are in your settings, I think, to be able to apply the science properly at different scales.

Of course- that's part of the point, after all. The MC doesn't want this in anyone else's hands, or to be put into mechanized mass production, though he could well do so (as well as miniaturize them to a ridiculous extent, with precision engineering having the potential to massively reduce the minimum achievable yantra size, and vastly increase the number of them which could be packed into a given area), since he soon realizes (both on his own, and after others start expressing their interest and trying to replicate their own versions), that bad guys armed with these weapons would be a pretty terrible thing to happen for the world in general.

• Your description of how the rod would be accelerated through the rails reminds me of a coilgun. I thought you would like to consider this for the design of your MC's weapon.
• Since the realgun can be an unwieldy beast (it's essentially a heavy sniper rifle with magical batteries attached to it), your MC will need other weapons for medium and close combat. Or just some sort of magical protection, at least to be able to stand on its own when required.

To sum up, yes your MC's railgun should be plausible although its not that simple as this huge gunz shoots stuff automagically. Although I'm aware that you're working on a light novel, I think using a bit those little details can help improve your story.

To be fair, the MC is the magical battery, and possessing a fairly healthy sense of self-preservation, wants to avoid medium or close combat whenever possible. And hypothetically, with the potential application of the same magical technology to accelerate and propel not only solid projectiles, but air as well in the same manner, carried to its logical conclusion by someone familiar with our world's action movies- couldn't he effectively create (and use the 'magical railgun' itself as) Iron Man-style repulsors- both as secondary weapons, and as a potential flight method?

 

[Eduardo Ficaria]

You have put some good thought on this SinghSong , very nice! Overall, I would say that, if I were in your shoes, I would set up the weapon in such a way that first, it made sense, and second but most important, would have a great potential for dramatic possibilities. From there on, you can go as crazy in details as you want with it, although I wouldn't recommend it for a light novel. Now, let's talk about more concrete questions.

...he is a genius by the standards of both worlds, in both science and technology and in magic.

Wouldn't be much more interesting that the guy is just smart enough to have an idea of the railgun but need other people to really build the thing? Like the late Steve Jobs, a guy who had the vision and some technical understanding at most, but not the knowledge or skills to build the tech itself. The genius trope is rather common, and trite I'd venture to say, in the japanese media. I mean, I think a character that has to engage with other characters to reach a certain goal, like developing a certain weapon, can provide your story with more interesing possibilities.

Not necessarily, regarding cool-down times- remember, real-world rail-guns (or coil-guns, for that matter) generate a ton of heat, and have huge energy requirements, because they work via electro-magnetic propulsion...

Since you mention bows, arrows and mystical terms that I mostly associate with cultures from India, I'll assume your isekai world is some sort of pseudo indomedieval magical one. Based on that, I think that you're overengineering a weapon that can be done with gunpowder tech at a much cheaper and scalable price. Maybe you're trying to apply the rule of cool here, trying to give a really nice weapon to your MC, but a mere Winchester rifle would be as cool in such a world and probably more practical.

At first, for the 1st generation/prototype model, I was contemplating whether or not to even have a barrel at all, let alone a muzzle- with just the two rails needed to propel the projectile, along with some way to keep them equidistant along their length, and some measure of inaccuracy accepted as a given (basically, so long as it's still an improvement on the accuracy of a crossbow bolt, it'd still be 'good enough'), could this potentially reduce the friction, and allow the hot plasma to dissipate more effectively? Or would the backlash be more likely to harm the user?

First, I'm no physicist or an expert in weaponry, but the barrel in such weapon would be important not to guide the rod, but to contain the rails/coils and protect them from external aggresion like weather phenomena, hits and so on. Also, the barrel would avoid having the really hot plasma to spread all over the place, thus eliminating the risk of burns to the user or nearby companions. Also, at the muzzle you might like to place something like a flash supressor or a muzzle brake. And regarding friction, remember that in a rail or coil gun the rod is suspended in a magnetic field, so it won't touch the barrel or the rails at all in its travel forward. Only the medium in which the rod is travelling will create friction, whether is vacuum, air, water or whatever.
On the other hand, the sonic boom probably could be quite harmful on its own since, at least, it can damage the ears of anyone too close to it. Think about how soldiers that handle cannons, pilot tanks or work in carrier decks have to wear headphones to protect their ears from noise damage.

...the yantras/runes are effectively all-purpose particle accelerators- as such, if they're accelerating the air enveloping the projectile to the same degree than they're actually accelerating the projectile itself, would air resistance, and the resulting hot plasma generation, actually be an issue within the barrel/between the rails at all? Or would it just result in a flash (and/or sonic boom from accelerating the air alone, even when the magazine's empty, adding a bit of versatility and close-range melee option for the weapon) once it's actually left the barrel?

I don't think you want a weapon that can accelerate just anything that goes into the barrel. In a railgun, the rod floats in the magnetic field because it has been made with a concrete set of materials that are affected by such field in a very concrete way. If your weapon is not doing that, then it's not a railgun-like weapon but something else. In fact, I think that that thing you say about accelerating particles out from thin air would be something closer to a Star Wars blaster: superheated plasma concentrated and projected by electromagnetic means.

It wouldn't have an exceptionally large magazine, but considering that there's no need for propellant, it could still well be markedly larger than an equivalent sniper/anti-material rifle the same size (say, 20-30 rounds, rather than 10-15)...

The problem is that if you want lightweight bullets, that means you'll have to give them an inversely proportional acceleration so they can have real penetration capability. In other words, less weight, more acceleration, and a longer barrel. Also, if the bullet is too light it might not be able to flight straight for long, no matter the speed it has, since the friction with air could be too much for it to overcome. On the other hand, the heavier the bullet, the more energy you'll need to accelerate it, but it will be more powerful and stable in flight.
And regarding the recoil, a rail or coil gun don't have recoil at all. There's no detonation, therefore there's no kickback. You could think that the superheated plasma could provoke some recoil, and probably does, but I don't know for sure.

...The MC doesn't want this in anyone else's hands, or to be put into mechanized mass production, though he could well do so...

In the very moment he shows up his weapon to a rather powerful and smart enemy, they'll start wondering how to make something similar, specially in a world with advance magic (which is nothing more than science with a superstitious name). They might take longer, and also it would depend on how you want to write your story, but throughout history you see how powerful neighbouring countries have more or less keep the pace with each other. War techniques, weapons and many similar things end up crossing frontiers sooner or later. Another I would say here is try to make the tech fitting to the world, in the sense of not making it too magically convenient or you'll end having a problem of cheapening the story due to making things too easy for your MC and allies. There must be tradeoffs: for instance, if your magical railgun can selfgenerate bullets automagically, make it so that the weapon ends getting so hot after a few shots that the user either has to wait some time, pour quite a lot of water, or use some sort of limited but highly efficient coolant (like you can do to your mech in the Mechwarrior videogames, for reference).

To be fair, the MC is the magical battery, and possessing a fairly healthy sense of self-preservation, wants to avoid medium or close combat whenever possible...

A battery with such use will suffer quite a lot of wear, since it has to discharge a lot of energy at once and reload as fast as possible. Bear that in mind for your character, it will limit what he can do in a battle if he sticks to just use the railgun and also will affect him physically, mainly in the nervous system probably. Also remember that a battle is a rather dynamic situation, in which you'll character will surely be exposed to close range fights. I imagine you have given him some companion that acts as his protector for those cases.Then, they'll have to learn to work in tandem: MC makes the shot, then they move somewhere else, with his protector opening the road for him. If this is the case, you could have a good chance to show the guts and smarts of your MC when he doesn't have such help and ends up facing an exclusively close quarters battle.

...And hypothetically, with the potential application of the same magical technology to accelerate and propel not only solid projectiles, but air as well in the same manner, carried to its logical conclusion by someone familiar with our world's action movies- couldn't he effectively create (and use the 'magical railgun' itself as) Iron Man-style repulsors- both as secondary weapons, and as a potential flight method?

Ah, there you're talking about rocket jumping, although I would advise against it very much. The iron man armor protects its user from its own repulsor jets, meanwhile your weapon just expels rods at a very high speed without any kickback whatsoever... That would leave a very nice crater on the ground the user was standing on a second earlier. So no, no railgun jumping for your MC, unless you want him to rest in burning pieces in an early grave!

So, as a recap of all of the above, just make that railgun a balanced weapon with understandable tradeoffs, believable for the settings and that your MC cannot spam on every battle situation he encounters. Also, I would go against making the MC superlative: of course he can be good at some things (like being a professional soldier or just have some decent experience at science), and learn more over time, but it's more engaging when characters have to struggle (together) with a limited and somehow realistic (within the settings) set of skills to solve the situations you put them in.

 

[Eduardo Ficaria]

Just a small note regarding the sonic boom. The crack of a whip is a supersonic boom, so that could help you to put in perspective how big of a boom you could get from your railgun rod. Check some videos on youtube to get a better sense of it.

 

[Patrick-Leigh]

I think the idea is plausible and it would not strain my ability to suspend my disbelief if you handled it in the way you’re proposing. I agree with Eduardo Letavia that you MC having assistance making the rail gun is more in line with real world examples like Steve Jobs. I’m having my own MC do something similar: She isn’t coming up with radical, new ideas, she’s just finding new ways to combine and utilize ideas that have been around for some time. In particular, she’s good at concatenating Enchantments (chaining them into a sequence) so she only has to activate one to get the ball rolling. Your MC having help would also give other characters more to do in the story and provide them with moments to shine. It’s okay to have hyper-competent characters, but you have to make sure they don’t render other characters irrelevant.

 

[SinghSong]

I think the idea is plausible and it would not strain my ability to suspend my disbelief if you handled it in the way you’re proposing. I agree with Eduardo Letavia that you MC having assistance making the rail gun is more in line with real world examples like Steve Jobs. I’m having my own MC do something similar: She isn’t coming up with radical, new ideas, she’s just finding new ways to combine and utilize ideas that have been around for some time. In particular, she’s good at concatenating Enchantments (chaining them into a sequence) so she only has to activate one to get the ball rolling. Your MC having help would also give other characters more to do in the story and provide them with moments to shine. It’s okay to have hyper-competent characters, but you have to make sure they don’t render other characters irrelevant.

Thanks. And yeah, chaining enchantments into a sequence is how the proposed concept weapon works too- pretty coincidental, eh? To be fair, regarding the MC being 'hyper-competent', it's actually my intention to explicitly not to make him like that- quite the opposite in fact, at least at first. Plenty of the potential design flaws and gaps in the 'magical railgun (v.1.0)' were intentional, with the original design set to be developed and refined into the second design by way of the MC learning through failure.

The magical inter-dimensional mind-meld though, which takes place via an artifact (crafted by the MC's original pre-merger self in the magical world, as a semi-failed, deeply flawed personal project to create something analogous the 'Hopper' device from the Long Earth series), while it does have its advantages (e.g, the combining of both minds' processing power, sets of knowledge and memories into one merged stream of consciousness, effectively doubling his intellectual capacity) does have a ton of drawbacks as well.

For instance, whilst it enables him to live both lives in both worlds to the fullest (with the MC crossing back and forth by default, awakening/regaining consciousness on schedule in one world after having fallen asleep/unconscious in the other), he also loses the ability to dream, increasingly suffers from lethargy upon waking up, and effectively mentally ages 1.5-2x quicker than normal (halving his maximum remaining predicted lifespan- unless, that is, he can find some solution to compensate for, or work around, this over in the magical world, without breaking the mind-meld and splintering his consciousness in the process).

And though the merger also divides both his selves' magical capacity and reserves evenly between both his bodies in both world, granting him the ability to use and create magic in the mundane parallel world (i.e, our world), it also almost halved the magical capacity and reserves originally possessed by his pre-merger self in the magical world, with the mechanic also effectively halving his magical growth and regeneration rate, along with any experience points he gains. What do you reckon- are these going to be big enough downsides/handicaps to balance out his increased intellectual capacity?

 

[Patrick-Leigh]

Thanks. And yeah, chaining enchantments into a sequence is how the proposed concept weapon works too- pretty coincidental, eh? To be fair, regarding the MC being 'hyper-competent', it's actually my intention to explicitly not to make him like that- quite the opposite in fact, at least at first. Plenty of the potential design flaws and gaps in the 'magical railgun (v.1.0)' were intentional, with the original design set to be developed and refined into the second design by way of the MC learning through failure.

The magical inter-dimensional mind-meld though, which takes place via an artifact (crafted by the MC's original pre-merger self in the magical world, as a semi-failed, deeply flawed personal project to create something analogous the 'Hopper' device from the Long Earth series), while it does have its advantages (e.g, the combining of both minds' processing power, sets of knowledge and memories into one merged stream of consciousness, effectively doubling his intellectual capacity) does have a ton of drawbacks as well.

For instance, whilst it enables him to live both lives in both worlds to the fullest (with the MC crossing back and forth by default, awakening/regaining consciousness on schedule in one world after having fallen asleep/unconscious in the other), he also loses the ability to dream, increasingly suffers from lethargy upon waking up, and effectively mentally ages 1.5-2x quicker than normal (halving his maximum remaining predicted lifespan- unless, that is, he can find some solution to compensate for, or work around, this over in the magical world, without breaking the mind-meld and splintering his consciousness in the process).

And though the merger also divides both his selves' magical capacity and reserves evenly between both his bodies in both world, granting him the ability to use and create magic in the mundane parallel world (i.e, our world), it also almost halved the magical capacity and reserves originally possessed by his pre-merger self in the magical world, with the mechanic also effectively halving his magical growth and regeneration rate, along with any experience points he gains. What do you reckon- are these going to be big enough downsides/handicaps to balance out his increased intellectual capacity?

Coincidence? Maybe, but it could also be that great minds think alike. As for the downsides to your MC's increased intellectual capacity, I think they work pretty well. The only one I don't like as much as the others is it reducing his lifespan, at least in a literal sense. Our brains have more than enough storage capacity for much longer lifespans than we have, it's just that the aging process causes them to deteriorate before we reach our maximum memory capacity. However, chronic stress from having to live two lives simultaneously would definitely take its toll on his body. He's got two brains, essentially, but even though they're resting physically, his psyche isn't. From his perspective, he's not really getting any sleep, so, psychologically and emotionally, he's not getting any breaks. That's going to burn a guy out pretty fast and stress him out considerably. That stress, in turn, can start to affect his physical bodies. It'd be interesting if the effects were different on each body. I'd recommend do some research on the effects of chronic stress to get some ideas.

 

[Mad Swede]

To add a little to Eduardo Letavia's comments. You've been thinking of the sort of railgun that the US and other countries are still developing. But you might consider a variant, something along the lines of a modern roller coaster. The latest ones use a series of electromagnets to accelerate the roller coaster train. Using something mounted on rails as a launcher would remove the need to keep the rails exactly parallel and would enable you to shoot several different types of ammunition. You'd have to find a way of getting it off the wheels, and it wouldn't go supersonic, but it would generate a lot less heat and might be more in line with the overall technology level in your world.

 

[Eduardo Ficaria]

So you have two MCs for the price of one, right? I don't think it would be as straightforward as having doubled the intellectual capac

To add a little to Eduardo Letavia's comments. You've been thinking of the sort of railgun that the US and other countries are still developing. But you might consider a variant, something along the lines of a modern roller coaster. The latest ones use a series of electromagnets to accelerate the roller coaster train. Using something mounted on rails as a launcher would remove the need to keep the rails exactly parallel and would enable you to shoot several different types of ammunition. You'd have to find a way of getting it off the wheels, and it wouldn't go supersonic, but it would generate a lot less heat and might be more in line with the overall technology level in your world.

Yes, that would be an alternative, but there's the important detail of having a cost effective weapon. If gunpowder or equivalent less complex and cheaper magic-based tech can do the job of shooting stuff at subsonic speeds, there's little point of building something far more complex, more expensive, harder to maintain, and maybe even heavier, to get the same result. I mean, magnetic levitation demands rare materials or alloys and very specialized skills to build it properly, even if you use magic for some of its parts.

On the other hand, I've remembered another type of weapon that could be used as a model for your railgun, SinghSong : the neddlegun or flechette gun and also the tranquilizer gun. Take a look at those links, I think you'll find them inspiring.

As a final thought about the main question of this thread, the railgun will only be plausible if the settings of your story allow for it naturally. For instance, I wouldn't expect a railgun in the Hyborian Age of Conan at all, but it would feel fine to read about magical arrows there.

Regarding the mind meld, be careful of not forgetting that you are handling two different characters. What happens when one personality comes active? Does the other mind go to the vacant body/brain? Is there some sort of mind limbo? If the mind meld process is not good enough, the active brain who ends having the two personalities at once would feel like suffering schizophrenia. Consider that those two minds will have different thought processes; in the end they're beings from different planets that have had different life experiences. And I don't want to go deeper by considering the neurological differences between the two MCs biologies... Also, I don't see how the isekai MC can know that his lifespan will be reduced to a half because of the mind meld, isn't he the first one trying it, at least with that particular technique of his?

 

[Don Coyote]

I get this a weapon for a magical world, but that doesn't mean the laws of physics are completely negated.

Every time you shoot the gun, it'll need some time to cool down.

Why? Firearms do not need to cool down every time they're shot and they generate more heat than a railgun does. Depending on how the railgun stores its power, it may need a recharge time but that's a different issue.

Heat can be controlled by rate of fire. In real life, a shooter can dump a mag of thirty rounds without pause which will heat up the rifle but won't stop the shooter from swapping mags and dumping another 30 rounds. After that, the barrel will be hot enough to burn skin but that's what hand guards are for.

So, if your railgun warms up as fast as a real firearm, the shooter can crank off a lot of rounds before it heats up enough to fail.

Also, in a real railgun the projectiles get shot at extremely high supersonic speeds, creating really hot plasma due to friction with air. Now imagine shooting such a thing in front of your face (or at a rather short distance).

Railguns can fire projectiles at any velocity, from less than walking speed all the way up to what the technology will bear. It's much more practical to design this railgun to fire at the same velocity as a modern firearm- about 3000 fps. Railguns have the added benefit of firing projectiles of the same mass and velocity as a firearm but without gunpowder. This reduces recoil about one third to one half.

How would you protect the user from the flash? I think you could go for an exaggeratedly flared muzzle, taking inspiration from Blunderbusses for instance.

At practical velocities, I don't think there's much of a flash to protect the shooter from.

PS- Blunderbuss type muzzle flares are lame.

If the weapon has a magazine, I don't think it will be very big. This means limited rounds per mag, as it happens with real sniper rifles, compared with assault rifles. Of course, this depends on the caliber of the rods your MC is planning to use.

First, railgun ammo will be smaller than ammo for firearms. Ammo for firearms has to have a case to hold powder, primer and bullet. Railgun ammo consists only of the bullet (projectile). A small magazine can hold more railgun ammo. Also, a sniper rifle can have a magazine that holds as many rounds as a so-called "assault rifle".

Weight. If a sniper rifle is already a heavy thing, imagine a railgun. Also, take into account the weight of the ammunition. This means that your MC won't be able to carry much ammunition around.

Why does a magic railgun have to be as heavy as a dedicated sniper rifle? (Some sniper rifles are nothing but an infantry rifle with a magnified scope.) This railgun is driven by the laws of magic, not the laws of electro-magnetism. If it has to be massive to hold the energies and generates excessive heat, why doesn't that extend to other magical artifacts?

Ammo for the railgun will be very light compared to firearm ammo. It only needs to be the projectile. Railgun ammo doesn't have to be cannonballs.

If the weapon is completely custom made, this means that no one but the MC is able to fix it when it breaks, or to make the ammunition with the proper specs. Also, think about the rarity of the tools, materials, pieces and spells used to build the weapon: this makes its maintenance a really tricky thing.

Ammo for a railgun is easy-peasy. It can be as simple as a lead ball. Longer, pointy bullets have better ballistics but will be more complicated to make, but doable in a world where a railgun is possible.

One could say that weapons like these are long range in nature, and shorter or smaller versions of it may or may not get the most of the potential benefits of the basic design. It all goes down on how advanced are in your settings, I think, to be able to apply the science properly at different scales.

If the magical railgun has to be long to be effective, yes it will be cumbersome at near melee ranges. But it's possible to make this railgun effective from melee range to 300 yards or more without disturbing suspension of disbelief.

Since the realgun can be an unwieldy beast (it's essentially a heavy sniper rifle with magical batteries attached to it), your MC will need other weapons for medium and close combat. Or just some sort of magical protection, at least to be able to stand on its own when required.

Considering what's needed to make a magical railgun be combat effective, it's not a given it needs to be heavy and cumbersome. If a magical battery needs to be made, more can be made and incorporated into the the magazine as the bullets now take up far less room than conventional ammo. When you swap a mag, you also swap batteries.

If the rail gun is powered by magical batteries, that assumes they need to be recharged after being discharged? This fits the convention of technology, but does it fit how magic works in this world? Do magic items need to be recharged after use? How are they recharged? If it's a matter of the engraved patterns make magic useable, there's no reason for a magical battery. In fact, if I understand SinghSong correctly, the railgun is powered by the magic of the engraved yantras used to accelerate the projectiles.

SinghSong, your magic railgun is more than doable. Make it amazing, but don't make it weird, cumbersome and complicated to keep it from being over-powered.

Oh- anyone developing a manportable railgun is going to be spending time at the range shooting it. Your character may not have experience shooting in combat, but he will be a shooter. Why build a rifle if you aren't?

 

[Mad Swede]

I get this a weapon for a magical world, but that doesn't mean the laws of physics are completely negated.

Why? Firearms do not need to cool down every time they're shot and they generate more heat than a railgun does. Depending on how the railgun stores its power, it may need a recharge time but that's a different issue.

Heat can be controlled by rate of fire. In real life, a shooter can dump a mag of thirty rounds without pause which will heat up the rifle but won't stop the shooter from swapping mags and dumping another 30 rounds. After that, the barrel will be hot enough to burn skin but that's what hand guards are for.

So, if your railgun warms up as fast as a real firearm, the shooter can crank off a lot of rounds before it heats up enough to fail.

Er, no. Whilst you can fire something like a machine gun very fast, the heat build-up means you have to cool the barrel. If you don't then you get barrel droop and increased barrel wear, both of which reduce accuracy. It's an even bigger problem with artillery, where long engagements can lead to significant barrel wear.

So depending on how the magical rail gun is formed, and where and where it is used, heating may be an issue.

Railguns can fire projectiles at any velocity, from less than walking speed all the way up to what the technology will bear. It's much more practical to design this railgun to fire at the same velocity as a modern firearm- about 3000 fps. Railguns have the added benefit of firing projectiles of the same mass and velocity as a firearm but without gunpowder. This reduces recoil about one third to one half.

Recoil will still be an issue, and a big magical rail gun (and/or one which fires at very high speeds) will need to be built and mounted to absorb the recoil. It isn't a trivial problem.

First, railgun ammo will be smaller than ammo for firearms. Ammo for firearms has to have a case to hold powder, primer and bullet. Railgun ammo consists only of the bullet (projectile). A small magazine can hold more railgun ammo. Also, a sniper rifle can have a magazine that holds as many rounds as a so-called "assault rifle".

Why would it be smaller? Surely that depends on what you're planning to shoot at?

Ammo for a railgun is easy-peasy. It can be as simple as a lead ball. Longer, pointy bullets have better ballistics but will be more complicated to make, but doable in a world where a railgun is possible.

The ammo isn't easy. The problem is that at high muzzle velocities you need a very well formed projectile, otherwise the projectile will start to tumble and then break up. Even if it doesn't break up the tumble reduces the range and accuracy, often to the point where you don't hit the target.

What SinghSong mentioned in his original post was using what he called kinetic impactor rods as ammunition. That, to me, isn't a bullet; it's more like the rod in what we professionals call a discarding sabot round, of the type you use in anti-tank weapons. Those rods are made of very dense metal, originally tungsten and these days depleted uranium. They work on the principle that when the rod hits the target the velocity of the rod in combination with its density turn it into a jet of plasma which burns through the target. Making projectiles like that requires a very high degree of machining accuracy in manufacture, and it also needs advanced metalurgical skills.

The fact that you have the magical ability to accelerate something doesn't mean you have the aerodynamic or metalurgical knowledge to build a weapon which can use them. In theory a scientist could have built a rail gun in the late 1800s, there was enough theoretical knowledge about electromagnetism to work out the basic principles. But they didn't have knowledge about high speed aerodynamics and they didn't have the metalurgical knowledge or the manufacturing technology to build the gun or the ammunition.

So yes, the magical rail gun is doable - in theory. But does the technology exist to build it?

 

[Eduardo Ficaria]

Realizing that I probably had some serious misconceptions about the railgun, I looked for a homemade one on youtube and I found this very illustrative video on a channel called Hacksmith Industries that can give all of us in this thread an idea of what implies to make such a weapon in a small size. And, around a year later, the same people made a coilgun rifle. For reference, here you have a video about the US Navy railgun.

Things to notice in those videos:

• With the coilgun there's no recoil at all. On the other hand, with the railgun seems to depend mainly on how the initial acceleration is given to the bullet/rod/sabot: if you use a detonation, you'll get the expected kickback from it, but in the case of the air-propelled hacksmith version you won't feel much at all.
• Friction is a huge issue in the railgun, the sabot's casing touches the rails in all its travel through the barrel, which can inflict serious damage to the rails from the heat generated. This reduces its usability significantly. On the other hand, it seems to me that it would be easier to design a coilgun able to handle heat better than the railgun.
• The high-tech work required to make the weapons is impossible to ignore. In both cases they need not only specialized materials and pieces, and high precision tools, but also more advanced tech like microchips for things like regulating the power charged in the batteries or capacitors.
• The bullets shot by the hacksmith weapons don't pack much of a punch and don't fly straight, just kind of tumble forward through the air. Probably this is more a question of lack of power in the batteries/capacitors rather than an aerodynamic problem with the bullets themselves (which I don't discard at all). But more electricity also means more heat in the discharge circuit (dont' forget that electrons also have friction while traveling through cables, that's how classic lightbulbs work), which not any material can resist.

So, based on what I've seen, Don Coyote , I have to say that your proposal wouldn't cut it for this kind of weaponry. You can hadwaive with magic all the problems of this tech, but wouldn't that cheapen the weapon and its dramatic possibilities within the story? It would be like playing Doom in God mode with infinite ammo, not exactly the most exciting experience to do in a FPS.

For the weapon to be plausible it must have believable tradeoffs in its characteristics and capabilities. Like Mad Swede has pointed out already, your weapon's tech, magical or not, has to be related to some knowledge already present in the settings. I mean, you cannot work with electricity if you don't know about electrons, right? So, SinghSong , in the end is up to you how you want to play with this. There's no need in your light novel to get to the level of detail we've got here but, if the weapon is going to be relevant and used frequently in your story, I think it will be good if you base it in the real tech. It will save you time thinking about how the weapon should be and behave or how it would degrade with extended use. Of course, use magic for things like the energy source or to make the special alloys needed for the weapon or the bullets, but just don't go overboard or it might hurt your story.

 

[Don Coyote]

Er, no. Whilst you can fire something like a machine gun very fast, the heat build-up means you have to cool the barrel. If you don't then you get barrel droop and increased barrel wear, both of which reduce accuracy. It's an even bigger problem with artillery, where long engagements can lead to significant barrel wear.

Barrels do not start dropping until the steel reaches temperatures in it's plastic stage. A machinegun can be fired in controlled bursts can fire more rounds at a lower temperature than if the shooter simply holds the trigger down until the machinegun runs out of ammo. I've put 500 rounds through a semiautomatic rifle in an afternoon and barrel temps never got anywhere near enough to cause barrel drop. That's because the rate of fire was much slower. Still, I've put a coupe hundred rounds through a machinegun in a single range session without causing barrel droop. (That doesn't make me an expert machinegunner.)

Barrels heat up when shot, but they also radiate heat.

So depending on how the magical rail gun is formed, and where and where it is used, heating may be an issue.

Yes. But not after a single shot. By controlling the rate of fire, quite a few shots can be made without heat being an issue.

Recoil will still be an issue, and a big magical rail gun (and/or one which fires at very high speeds) will need to be built and mounted to absorb the recoil. It isn't a trivial problem.

But it doesn't have to be a big magical railgun. I believe SinghSong is imagining a man portable gun, not an artillery piece. It doesn't have to fire at speeds faster than a conventional rifle. Recoil would be more than manageable.

If you take a 8 pound conventional rifle and fire a 150 grain bullet from it at about 2800 fps (more than enough for an effective infantry rifle) free recoil is about 15 ft/lbs. Fire the same bullet at the same velocity from a railgun, recoil will be somewhere between 7.5 to 10 ft/lbs because you don't have the velocity & mass of the powder charge adding to the recoil.

Why would it be smaller? Surely that depends on what you're planning to shoot at?

It's smaller because it's made to be a man portable infantry rifle.

The ammo isn't easy. The problem is that at high muzzle velocities you need a very well formed projectile, otherwise the projectile will start to tumble and then break up. Even if it doesn't break up the tumble reduces the range and accuracy, often to the point where you don't hit the target.

Again, the railgun doesn't have to launch its payload at fantastic speeds. Just fast enough to be good as an infantry rifle.

The bullets don't need to be more complicated than a lead ball. Figure out a way to put a spin on it to stabilize it past 75 yards. Copper jacketed spitzers aren't hard to make either. Or a small finned dart.

What SinghSong mentioned in his original post was using what he called kinetic impactor rods as ammunition. That, to me, isn't a bullet; it's more like the rod in what we professionals call a discarding sabot round, of the type you use in anti-tank weapons. Those rods are made of very dense metal, originally tungsten and these days depleted uranium. They work on the principle that when the rod hits the target the velocity of the rod in combination with its density turn it into a jet of plasma which burns through the target. Making projectiles like that requires a very high degree of machining accuracy in manufacture, and it also needs advanced metalurgical skills.

"Impactor Rod" is just a fancy word for "Bullet" or "Projectile". Discarding sabot projectiles are nothing but bullets with sabots that peel away after a few feet downrange. The projectile in the sabot can be anything from a copper jacketed pistol bullet (the type some modern muzzleloaders use for hunting) to tungsten steel or DU penetrators (kinetic kill) to any variety of explosives and pyrotechnics.

While specialized projectiles require more precise manufacturing techniques to assure best performance, no such projectiles are required in a man portable magic railgun used against simple melee weapons and archers. The railgun in this case isn't made to break modern armor or as a siege weapon.

Even if this railgun is intended to be used as field artillery, using it to generate nothing but outrageous speeds means it can't be used for indirect fire.

The fact that you have the magical ability to accelerate something doesn't mean you have the aerodynamic or metalurgical knowledge to build a weapon which can use them. In theory a scientist could have built a rail gun in the late 1800s, there was enough theoretical knowledge about electromagnetism to work out the basic principles. But they didn't have knowledge about high speed aerodynamics and they didn't have the metalurgical knowledge or the manufacturing technology to build the gun or the ammunition.

We ain't using electromagnetism. We're using magic. The creator understands how to make magic works and is imaginative enough to create something new. It didn't take long after the creation of blackpowder before it was used to drive projectiles. It wasn't long after the invention of the muzzle loader before some forgotten gunsmith started looking for ways to increase a gunner's rate of fire and how to pack more shots in the gun.

So yes, the magical rail gun is doable - in theory. But does the technology exist to build it?

Yes, of course. The world uses magic engravings to create mechanical effects.

It would be unbelievable (or as long time D&D players would say- broken) to make a man portable railgun with the power of a field artillery piece. But a shoulder fired magical repeater matching blackpowder rifles in ballistics and terminal performance is very believable. In fact, it would be believable if it were stretched to match the performance of a modern infantry rifle.

 

[Don Coyote]

With the coilgun there's no recoil at all. On the other hand, with the railgun seems to depend mainly on how the initial acceleration is given to the bullet/rod/sabot: if you use a detonation, you'll get the expected kickback from it, but in the case of the air-propelled hacksmith version you won't feel much at all.

No recoil violates the laws of physics. "For every action, there is an equal and opposite reaction".

Friction is a huge issue in the railgun, the sabot's casing touches the rails in all its travel through the barrel, which can inflict serious damage to the rails from the heat generated. This reduces its usability significantly.

Perhaps. What is the sabot made from? How much heat is generated? How much heat needs to be generated to inflict significant damage to the rails?

In any case, slowing down the velocity will reduce heat generated.

The high-tech work required to make the weapons is impossible to ignore. In both cases they need not only specialized materials and pieces, and high precision tools, but also more advanced tech like microchips for things like regulating the power charged in the batteries or capacitors.

Technology? We don't need no steenkeen technology. We have magic and the power of author's FIAT!

The bullets shot by the hacksmith weapons don't pack much of a punch and don't fly straight, just kind of tumble forward through the air. Probably this is more a question of lack of power in the batteries/capacitors rather than an aerodynamic problem with the bullets themselves (which I don't discard at all). But more electricity also means more heat in the discharge circuit (dont' forget that electrons also have friction while traveling through cables, that's how classic lightbulbs work), which not any material can resist.

It's a stability and aerodynamic problem. Projectile was launched in an unstable state, compounded by aerodynamic drag. Well, at such low velocities, it more likely a stability problem

So, based on what I've seen, Don Coyote , I have to say that your proposal wouldn't cut it for this kind of weaponry. You can hadwaive with magic all the problems of this tech, but wouldn't that cheapen the weapon and its dramatic possibilities within the story? It would be like playing Doom in God mode with infinite ammo, not exactly the most exciting experience to do in a FPS.

Not at all. I don't propose making the railgun the equivalent of man portable field artillery. That would be ridiculous. Just make it a magic infantry rifle.

For the weapon to be plausible it must have believable tradeoffs in its characteristics and capabilities. Like Mad Swede has pointed out already, your weapon's tech, magical or not, has to be related to some knowledge already present in the settings. I mean, you cannot work with electricity if you don't know about electrons, right? So, SinghSong , in the end is up to you how you want to play with this. There's no need in your light novel to get to the level of detail we've got here but, if the weapon is going to be relevant and used frequently in your story, I think it will be good if you base it in the real tech. It will save you time thinking about how the weapon should be and behave or how it would degrade with extended use. Of course, use magic for things like the energy source or to make the special alloys needed for the weapon or the bullets, but just don't go overboard or it might hurt your story.

It's fiction. It's magic. Why does the character have to understand electromagnetism if he understands magic? It works because the author says it does. Just don't violate the rules set forth in the universe and the readers will buy it.

 

[Mad Swede]

Barrels do not start dropping until the steel reaches temperatures in it's plastic stage. A machinegun can be fired in controlled bursts can fire more rounds at a lower temperature than if the shooter simply holds the trigger down until the machinegun runs out of ammo. I've put 500 rounds through a semiautomatic rifle in an afternoon and barrel temps never got anywhere near enough to cause barrel drop. That's because the rate of fire was much slower. Still, I've put a coupe hundred rounds through a machinegun in a single range session without causing barrel droop. (That doesn't make me an expert machinegunner.)

I've used machine guns in combat. Over here we use what we call Ksp88s (what the Americans call an M2HB), and in combat the sustained rate of fire is about 450-500 rounds per minute. At that rate of fire you have to change the barrel at least once an hour, otherwise it overheats. The heavy barrel does reduce the droop when it gets hot, but it doesn't prevent it, and what you don't ever do is drop the hot barrel when you've changed it for the cool one.

As for automatic rifles, in practice you don't achieve a sustained rate of fire of more than 10-15 rounds per minute in combat, simply because you can't swap targets any faster than that and because you have to keep changing the magazine.

Yes. But not after a single shot. By controlling the rate of fire, quite a few shots can be made without heat being an issue.

Well, that depends on the gun. Some of the extremely large guns developed by the Germans during the Second World War could only fire 10 rounds or so before they had to cease fire to allow the barrel to cool. Range is (in part) function of muzzle velocity, and high muzzle velocities generate a lot of barrel heat. In practice, with very large long range guns you end up doing a separate propellant calculation for each shell you fire (even at the same target) so as to allow for the effects of barrel heating.

The bullets don't need to be more complicated than a lead ball. Figure out a way to put a spin on it to stabilize it past 75 yards. Copper jacketed spitzers aren't hard to make either. Or a small finned dart.

That depends on velocity. The higher the velocity the better the shape of the round has to be to, otherwise it will tumble and/or break up. To put it in perspective, the old style Colt revolver so beloved of the western movies had a muzzle velocity of about 900 feet per second, sometimes less, depending on the bullet and black powder charge. A modern M16 has a muzzle velocity of more than 3 times that.

Which brings me back to my last point. Does the knowledge and technology exist to do produce the weapon and ammunition needed? Engraving a series of yantras into metal rails is one thing, boring and rifling a barrel is quite another. And does the technology exist to produce the jacketed round or a finned dart needed for stability?

"Impactor Rod" is just a fancy word for "Bullet" or "Projectile". Discarding sabot projectiles are nothing but bullets with sabots that peel away after a few feet downrange. The projectile in the sabot can be anything from a copper jacketed pistol bullet (the type some modern muzzleloaders use for hunting) to tungsten steel or DU penetrators (kinetic kill) to any variety of explosives and pyrotechnics.

They're a lot more than just simple bullets, there's far more to those rounds than that. Getting the sabots to discard cleanly without disturbing the flight (and hence accuracy and range) of the dart is not a trivial exercise, in fact its one which requires quite a lot of aerodynamic knowledge. And thats before you've optimised the shape of the dart for both aerodynamic efficiency and impact vapourisation.

While specialized projectiles require more precise manufacturing techniques to assure best performance, no such projectiles are required in a man portable magic railgun used against simple melee weapons and archers. The railgun in this case isn't made to break modern armor or as a siege weapon.

So we're not up against armoured troops then? If our enemies are wearing plate armour we need something which penetrates their armour, preferably at reasonably long range, so we can pick them off before they get close enough to overwhelm our defensive lines with numbers. The big advantage of something like a rail gun is its range, and any good commander will want to use that advantage.

Even if this railgun is intended to be used as field artillery, using it to generate nothing but outrageous speeds means it can't be used for indirect fire.

Of course it can be used for indirect fire. In fact, thats where you want good muzzle veolcity, so that you get the range. That way you can position the weapon further back and still hit the target, or position closer and get the height you need for penetration of a thick roof.

We ain't using electromagnetism. We're using magic. The creator understands how to make magic works and is imaginative enough to create something new. It didn't take long after the creation of blackpowder before it was used to drive projectiles. It wasn't long after the invention of the muzzle loader before some forgotten gunsmith started looking for ways to increase a gunner's rate of fire and how to pack more shots in the gun.

The first cannon were not reliable, and had a distressing tendency to blow up - the metallurgical skills needed to cast a cannon with enough strength to withstand repeated firings took some time to develop. It was even longer before the wire wound barrel was developed to allow for longer barrels and higher muzzle velocities. In fact, it took about 400 years from black powder appearing in the west to someone developing small workable revolvers and breech loader rifles.

Knowing the principles and the theory doesn't mean you have the technology to build something.

 

[Don Coyote]

I've used machine guns in combat. Over here we use what we call Ksp88s (what the Americans call an M2HB), and in combat the sustained rate of fire is about 450-500 rounds per minute. At that rate of fire you have to change the barrel at least once an hour, otherwise it overheats. The heavy barrel does reduce the droop when it gets hot, but it doesn't prevent it, and what you don't ever do is drop the hot barrel when you've changed it for the cool one.

You keep bringing up artillery and crew served weapons. They use a lot more gunpowder so of course they generate more heat.

I'm talking about a railgun the size of an infantry rifle.

If SinghSong wants a protaganist smart enough and dedicated enough to overcome the problems of designing a prototyping a magic railgun, yes it's possible to make it happen without breaking the rules of the world. Because Rule of Cool!

Singh, make it so!

 

[SinghSong]

So you have two MCs for the price of one, right? I don't think it would be as straightforward as having doubled the intellectual capac

No, it isn't quite that straightforward; but twice the memories, twice the memory capacity, and twice the processing power, makes for a significant improvement on either original, with the trans-dimensional mind-meld having turned his brain's operating system into the equivalent of a dual-core processor, which significantly improves his capacity to multi-task in particular. With both of his original selves having had Aspergers'/high-functioning autism, one to a barely noticeable extent and the other to a significant degree, he effectively becomes capable of multi-tasking as well as, or slightly better than, a normal person, whilst still retaining the ASD ability to concentrate upon each task at the same abnormal level of intensity, and to 'hyperfocus' on areas of particular interest (cases in point, the keen interests in R&D and weapons development which drive the MC to come up with the 'magical railgun' concept and create it in the first place).

Yes, that would be an alternative, but there's the important detail of having a cost effective weapon. If gunpowder or equivalent less complex and cheaper magic-based tech can do the job of shooting stuff at subsonic speeds, there's little point of building something far more complex, more expensive, harder to maintain, and maybe even heavier, to get the same result. I mean, magnetic levitation demands rare materials or alloys and very specialized skills to build it properly, even if you use magic for some of its parts.

On the other hand, I've remembered another type of weapon that could be used as a model for your railgun, SinghSong : the neddlegun or flechette gun and also the tranquilizer gun. Take a look at those links, I think you'll find them inspiring. [/QUORA]

Magical levitation, via yantric method, does demand rare materials, to an extent (along with the very specialized skills that the MC already possesses, significantly above the pre-requisite minimum level)- however, these rare materials are organic, with the dye of the Ti plant in particular being the most potent and useful. Aka in Proto-Austronesian as the kilála plant, or 'plant of knowledge', Ti plants are widely regarded as having sacred mystical or spiritual powers in various Papuan and Austronesian cultures, and attributed with the unique ability to absorb and accumulate ambient magical, soul and spirit energy, including the lost spirits and/or spirit energy of those who die in their vicinity- with several cultures IRL conducting rituals to purposefully enhance their potency by placing the souls of their dead, along with those of sacrificed animals, inside of them, uprooting and replanting them as boundary markers for claimed territories, as well as sacred groves, shrines, burial grounds and battlefield memorials. And the various cultivars (with green and red being the most common, and having the most folklore related to them, but purple, red and yellow cultivars also existing IRL, along with a few others) are commonly made into natural dyes, which are/were used as body paint, in tattoos, to decorate ritual objects, and in all manner of rituals (e.g, warding, protection, healing, purification, divination, fertility, luck, war, evil, necromancy etc).

Its consumption was originally extremely taboo (to a similar or greater extent than cannibalism, and mostly for the same reason), but lifted by several Polynesian cultures (IOTL) as a response to famine conditions (with the lifting of the taboo also believed to be tied to the development of the firewalking ritual), who started harvesting their ginger-like rhizomes and processing them into a sweet molasses-like pulp, which can be eaten like candy or used to produce a honey-like liquid used in various sweet treats as well as fermented to create alcoholic beverages, with Hawaiian Okolehao being the most famous of these (with Ti consumption also reputed to be the easiest and most effective way of increasing one's own magical/spirit energy, and notorious in folklore as being the primary method which dark shamans and necromancers derive their power from, across the rest of its native range beyond Polynesia- where it ranges from Bangladesh, to Mainland Southeast Asia, South China, Taiwan, Island Southeast Asia, New Guinea, and Northern Australia, having originated and been originally cultivated on New Guinea more than 10,000 years ago). As such, it's 'rare' in a sense, but also fairly cheap and easy to cultivate, with the dyes no harder to obtain than specific varieties of sugar in our world (albeit only sold at fairly extortionate prices on the open market, especially for the rarest dye colors, due to their importance and most of the production being nationalized and hoarded).

As a final thought about the main question of this thread, the railgun will only be plausible if the settings of your story allow for it naturally. For instance, I wouldn't expect a railgun in the Hyborian Age of Conan at all, but it would feel fine to read about magical arrows there.

Regarding the mind meld, be careful of not forgetting that you are handling two different characters. What happens when one personality comes active? Does the other mind go to the vacant body/brain? Is there some sort of mind limbo? If the mind meld process is not good enough, the active brain who ends having the two personalities at once would feel like suffering schizophrenia. Consider that those two minds will have different thought processes; in the end they're beings from different planets that have had different life experiences. And I don't want to go deeper by considering the neurological differences between the two MCs biologies... Also, I don't see how the isekai MC can know that his lifespan will be reduced to a half because of the mind meld, isn't he the first one trying it, at least with that particular technique of his?

Regarding the setting, it's basically a magic-punk world, at roughly the same technological level as the Victorian era, but with yantras rather than fossil fuels providing the impetus for early industrialization. And regarding the mind-meld, while they were two different characters beforehand, there wasn't a great deal of difference (otherwise it wouldn't have worked at all)- and the MC does indeed suffer from mild schizophrenia as a result, at least in the beginning, before this eases off as he gradually adjusts to his new mental landscape and situation. As for knowing that his lifespan'll be reduced by half- that's more of a vague estimate than a solid, set-in-stone professional diagnosis, which he himself ascertains after trying to gauge the negative health impact of the mind-meld, spurring him to try and cure or mitigate this as one of the main story arcs.

I'm kind of drawing from my own personal experience here, a bit- as someone with a combination of both Aspergers' and stress-induced epilepsy, who's done my research, I know my life expectancy's reduced by 25-30yrs, and that I'm virtually guaranteed to die of a stroke, if I don't die of anything else first (before making it into my 60's, if I manage to do so). Would I like to change that- would I change that, if I could? Of course. Have I been looking for ways to mitigate this, reduce the risks? Of course I have. Would I want to 'cure' it, if it involved having to rewrite my brain to work in a different way? No- it'd be a price too high to pay, and I'd rather go with the near-certainty of dying relatively young than effectively killing off who I am to become an entirely different person. And that's the character arc I'm aiming for with that element, with the prospect of premature death itself remaining far enough in the future not to present an imminent threat, but still closer than it would otherwise be, close enough for the character to think about his mortality.

 

[SinghSong]

I get this a weapon for a magical world, but that doesn't mean the laws of physics are completely negated.

Why? Firearms do not need to cool down every time they're shot and they generate more heat than a railgun does. Depending on how the railgun stores its power, it may need a recharge time but that's a different issue.

Heat can be controlled by rate of fire. In real life, a shooter can dump a mag of thirty rounds without pause which will heat up the rifle but won't stop the shooter from swapping mags and dumping another 30 rounds. After that, the barrel will be hot enough to burn skin but that's what hand guards are for.

So, if your railgun warms up as fast as a real firearm, the shooter can crank off a lot of rounds before it heats up enough to fail.

Railguns can fire projectiles at any velocity, from less than walking speed all the way up to what the technology will bear. It's much more practical to design this railgun to fire at the same velocity as a modern firearm- about 3000 fps. Railguns have the added benefit of firing projectiles of the same mass and velocity as a firearm but without gunpowder. This reduces recoil about one third to one half.

At practical velocities, I don't think there's much of a flash to protect the shooter from.

PS- Blunderbuss type muzzle flares are lame.

First, railgun ammo will be smaller than ammo for firearms. Ammo for firearms has to have a case to hold powder, primer and bullet. Railgun ammo consists only of the bullet (projectile). A small magazine can hold more railgun ammo. Also, a sniper rifle can have a magazine that holds as many rounds as a so-called "assault rifle".

Why does a magic railgun have to be as heavy as a dedicated sniper rifle? (Some sniper rifles are nothing but an infantry rifle with a magnified scope.) This railgun is driven by the laws of magic, not the laws of electro-magnetism. If it has to be massive to hold the energies and generates excessive heat, why doesn't that extend to other magical artifacts?

Ammo for the railgun will be very light compared to firearm ammo. It only needs to be the projectile. Railgun ammo doesn't have to be cannonballs.

Ammo for a railgun is easy-peasy. It can be as simple as a lead ball. Longer, pointy bullets have better ballistics but will be more complicated to make, but doable in a world where a railgun is possible.

If the magical railgun has to be long to be effective, yes it will be cumbersome at near melee ranges. But it's possible to make this railgun effective from melee range to 300 yards or more without disturbing suspension of disbelief.

Considering what's needed to make a magical railgun be combat effective, it's not a given it needs to be heavy and cumbersome. If a magical battery needs to be made, more can be made and incorporated into the the magazine as the bullets now take up far less room than conventional ammo. When you swap a mag, you also swap batteries.

If the rail gun is powered by magical batteries, that assumes they need to be recharged after being discharged? This fits the convention of technology, but does it fit how magic works in this world? Do magic items need to be recharged after use? How are they recharged? If it's a matter of the engraved patterns make magic useable, there's no reason for a magical battery. In fact, if I understand SinghSong correctly, the railgun is powered by the magic of the engraved yantras used to accelerate the projectiles.

SinghSong, your magic railgun is more than doable. Make it amazing, but don't make it weird, cumbersome and complicated to keep it from being over-powered.

Oh- anyone developing a manportable railgun is going to be spending time at the range shooting it. Your character may not have experience shooting in combat, but he will be a shooter. Why build a rifle if you aren't?

The main issue with yantras, in my canon, isn't so much heat, as it is degradation; physically, imagine them as the equivalent of reality-stretching rubber bands, rather than reality warping rocket fuel/propellant. So heating is still something of an issue, but the main technical wear-and-tear issue is magical degradation (analogous to oxidative degration for rubber and other elastomers), which either causes chain hardening/embrittlement (with the yantra/rune failing by cracking or snapping) or chain scission/softening (with the yantra/rune 'melting down' to become weaker and weaker over time), depending on the materials used (both in the magical inks/dyes used to create/etch the yantra, and the medium it's etched/engraved into). The former is far more common than the latter (with the latter being far more desirable, since it can effectively be fixed with ease by simply redrawing the yantra/rune again), with other issues such as charring (except in the case of tattooed yantras, which are purposefully designed to be charred) and color fading also reducing their effectiveness.

And they can also be compared with magical rubber bands, insofar as stretching a rubber band will cause it to release heat in an exothermic reaction, while releasing it after it has been stretched will lead it to absorb heat in an endothermic reaction, causing its surroundings to become cooler, in accordance with the Gibbs free energy phenomenon. Rearranging ΔG=ΔH−TΔS, where G is the free energy, H is the enthalpy, and S is the entropy, we get TΔS=ΔH−ΔG. Since stretching is non-spontaneous, as it requires external work, TΔS must be negative. But since T is always positive (it can never reach absolute zero), the ΔS must be negative, implying that the rubber in its natural state is more entangled (with more microstates) than when it is under tension. Thus, when the tension is removed, the reaction is spontaneous, leading ΔG to be negative. Consequently, the cooling effect must result in a positive ΔH, so ΔS will be positive there.

The same is also true of yantras in this setting, which work according to a similar mechanic. Effectively, they're constructs purposefully designed to invoke magical/quantum entanglement, with the non-spontaneous external work conveyed by the users' magical energy to stretch (/energize/activate) them, placing them under tension, and also causing them to generate heat. Which is then removed (/released, either via the user simply withdrawing their magical energy from them for the simplest, most basic yantras- a la the "RELEASE!" proclamation commonly used by magic users in anime/manga- or by other methods for more sophisticated yantras, including time-release mechanisms, pulling triggers and pressing buttons), invoking the intended reaction (magical function) spontaneously, as well as absorbing heat in their vicinity (by default- though purpose-created yantras specifically to increase and decrease the ambient levels of thermal energy in their immediate vicinity do exist, and are fairly commonplace, to the extent where the magical yantric equivalents of gas stove cookers, kettles, and fridge-freezers are luxury hand-crafted household appliances),

As such, the barrel heating could be an issue, insofar as there'd be a definite limit on how much magical power the MC/wielder'd be able to pump into charging up and re-charging the yantric 'magical railgun' (themselves, with their own magical energy/ 'mana' reserves serving as the main battery), and how quickly the MC'd be able to do it without burning it out in the process (so continually charging it to rapid-fire non-stop like a belt-fed machine gun's not likely to happen)- though that in itself isn't too much of an issue, since his magical power levels have been reduced to a fairly average level. After doing so, though, any heat generated by charging the yantras themselves should have a chance to dissipate, provided the weapon's charged well in advance (or if the MC's willing to blow the additional magical energy investment required to add that function, a build-in set of cryogenic yantras could incorporated and activated to do this quicker). And when firing it, whilst the target hyper-velocities involved would generate a great deal of heat, the releasing of the yantras themselves, just like the releasing of an elastic band, is actually an endothermic, cryogenic reaction. Enough to compensate for the heat released via friction between the air and the projectile itself, even if it is shooting off hyper-sonic kinetic kill projectiles? It's not impossible...