Worldbuilding: No Explosives Greater Than Black Powder

[Darmalus]

I've got a fantasy world with wizards and dragons and such, but most armies are still mostly mundane due to how hard it is to train up a combat capable battle mage. The setting takes a lot of elements from Spelljammer, so it's got everything from stone age hordes to steampunk.

One idea we had was that there are no explosives more powerful than black powder, and the universe enforces this. Bring some antimatter from another universe and set it off, it gives a boom as big as an equal amount of black powder and any extra energy just goes away. I'll apply this to fuels, but I'm honestly not sure if they would be effected or not. The universe gives a pass for living things and magic, so no one drops dead because a metabolic process is suddenly less energetic or stuff like that.

There are many different explosives, they just go all boom like black powder. Some are clean burning, make no smoke, make purple smoke, smell like roses, etc. Assume designers use an appropriate powder.

My question is, would this change how military (or other) technology functions significantly? Or would bombs just be weaker and bullets need more powder? I ask because one faction has the theoretical military capabilities approximately that of a WW1 power, planes tanks, machine guns and so forth. I'm curious if any of these will be noticibly altered by this limitation.

[Borgholio]

Bombs would be weaker, because modern chemical explosives are orders of magnitude more powerful than black powder. There would not be any nuclear weapons, long range rocketry or missiles. Rapid fire weapons would likely still be Gatling-style, but they'd still have semi-auto cartridge loading rifles and pistols.

In addition, if you include combustible materials such as gasoline and jet fuel, there would be no mechanized warfare, no air power, and no space flight.

In short, think about the style of warfare circa late 1800's before they developed motorized vehicles and that's about as far as you'd get.

[Darmalus]

Would fuels be effected that badly? I know that the energy density of gas is much higher than gunpowder, but I'm more concerned with energy released per second than energy contained.

Though an internal combustion engine is basically an explosion powered engine, so that may amount to the same thing in the end.

[Borgholio]

Yeah think of a Saturn V rocket. Basically the biggest non-nuclear bomb ever made...it is just released over time instead of all at once. If you're concerned with energy per second, then even simple gasoline puts out more energy than black powder, not to mention rocket fuel.

[Starglider]

There would not be any nuclear weapons

I would not be so sure about that. Implosion-type fission devices would not be possible, but gun type weapons would be. The necessary velocity for a uranium slug is approx 300 m/s, which is actually slower than the muzzle velocity of some of the later black-powder muskets. The device would be bigger, bulkier and heavier but still quite feasible.

~mad science finds a way~

[Borgholio]

Perhaps, but I took him literally when he meant "No explosions" bigger than gunpowder...and a nuclear chain reaction is a bit bigger.

[Darmalus]

Perhaps, but I took him literally when he meant "No explosions" bigger than gunpowder...and a nuclear chain reaction is a bit bigger.

True. It's a pound-for-pound limitation. 1 ton of uranium and 1 ton of gunpowder exploding would release the same energy, although the uranium would be much more compact due to it's density. The uranium might be more useful in some sort of anachronistic nuclear reactor.

[Sea Skimmer]

If the limitation applies to fuel, then I think humans all DIE, because as I recall the energy reactions involved in the human metabolism are higher energy density then most explosives, if only on a very small scale, and many foods certainly have higher energy density then blackpowder, though not all of them.

But the whole difference between an explosive we consider an explosive, as opposed to just an explosive hazard, and a fuel is that the explosive has its own integral oxidizer. Thus it can explode when contained at max packing density. Fuels like gasoline or sugar need oxidizer to react effectively, which comes from O2 out of the air. So if your using magic fiat for this, that can be a reasonable distinction.

As for weapons, you've functionally limited muzzle velocities to about 450m/s in reasonable weapons, though this can be a little higher if you allow brown powder. Brown powder is less energetic then blackpowder for the weight, but it had better pressure curve characteristics for artillery pieces. So for a short period in the 1870s and 1880s people were building brown powder guns with huge firing chambers for immensely huge powder charges to exploit this, just before the first smokeless powders appeared. This was also known as slow burning cocoa powder and several other use/user specific names.

Shrapnel shells will still work fairly well, but without high explosives its very hard to make shells that have good fragmentation. Blackpowder shells tended to burst into only a few dozen fragments, at best. Penetration of armor is also almost impossible, the friction will simply burst the blackpowder on impact, and only shallow penetration of earth, stone and concrete fortifications is possible. So if steel and concrete tech are unaffected, your going to have warships cruising around with armor that simply cannot be penetrated at all by any reasonable gunfire even with solid shot, and forts that are absurdly hard to break apart.

Shaped charges dont really work with low explosives, torpedoes will still work on ships, if being far easier to protect against, and I think a good fort is really only going to be vulnerable to sapping and mining. And earthworks will soak up levels of shellfire that make WW1 look lame at times. Which actually hapened in some of the Balkans wars anyway. Oh and you know barbed wire? That stuff kinda wont really break from blackpowder explosions, at all, so you'll have to cut it with shrapnel which is about the least efficient idea ever, so tanks will be badly needed, and tanks will be immune to all possible small arms even with very thin armor, and far more resistant to artillery fire... basically rolling death wagons on par with the first deployment on the Somme, if rather worse armed. Invest in landmines and anti tank ditches!

[MrDakka]

... tanks will be immune to all possible small arms even with very thin armor, and far more resistant to artillery fire... basically rolling death wagons on par with the first deployment on the Somme, if rather worse armed. Invest in landmines and anti tank ditches!

So WH40k tanks then?

With ineffective/no shaped charges, infantry are kind of screwed. How would infantry deal with tanks then? Thermite tipped lances?

[Darmalus]

Would tanks be plausible? Borgholio was saying the energy per second limit would prevent internal combustion engines from functioning.

[MrDakka]

If thats the case, then you can still have nuclear powered steam engines/radioisotope generators for locomotion. Or is nuclear energy out as well?

[Darmalus]

If thats the case, then you can still have nuclear powered steam engines/radioisotope generators for locomotion. Or is nuclear energy out as well?

Nothing forbids it. The universe just "deletes" any energy per second above that you would get from burning black powder if the source isn't alive or magic. I assume that this means steam engines still work, since gunpowder is mostly charcoal.

I concept of giant, nuclear powered land battleships make an appealing "boss monster" or "hero unit" for armies and other Big Bads.

[Serafina]

A very important factor would be construction - the development of better explosive allowed lots of massive construction projects that would otherwise be extremely difficult.
So you get a lot less channels, tunnels and all the other stuff that requires rock blasting.

Demolishing large building such as skyscrapers would be very hard to demolish - essentially they would have to be dismantled, unless you can live with the results of them falling down uncontrolled.

[Simon_Jester]

If thats the case, then you can still have nuclear powered steam engines/radioisotope generators for locomotion. Or is nuclear energy out as well?

Nothing forbids it. The universe just "deletes" any energy per second above that you would get from burning black powder if the source isn't alive or magic. I assume that this means steam engines still work, since gunpowder is mostly charcoal.

If it's energy per second, then steam engines still work normally. Internal combustion engines may or may not work.

Part of the problem is that this "just deletes" action is unclear. Does it "just delete" any energy produced by any given molecular or atomic reaction larger than the energy released by a single molecule of gunpowder combining with its oxidizer?

In that case fission does not work, nuclear energy does not work. The sun... does not work. Unless you use the old 19th century notion that the sun actually glows because of the heat of its own gravitational collapse... in which case it only lasts for about 10-20 million years.

On the other hand, maybe this "just deletes" is a macro thing: you can have a fuel or explosive with a higher per-molecule energy density than gunpowder, and release all of that energy slowly over time, because one kilogram of fuel releasing its energy over the course of ten seconds doesn't exceed the limit you get when one kilogram of gunpowder releases its energy over the course of one second.

In that case, internal combustion engines work, high explosives don't, and nuclear reactors probably work but may tend to be self-limiting and low-energy.

[Darmalus]

Yeah, it's a macro scale on average thing. I was wondering about IC engines simply because I understand they are basically explosion powered engines and gasoline has a much higher energy density than gunpowder. So I guess the question is that if you substituted an equal amount of gunpowder for fuel/air in the combustion chamber, would it still work? Yes, no, and yes but poorly can all lead to interesting and internally consistent technologies, which is really the goal in the end.

Their astrophysics are so wildly different from ours that it's not even worth worrying about.

[Borgholio]

If gasoline / diesel works just with the energy output of black powder, I suppose it could still run if the other properties of the fuel are unaffected. It'd just be a somewhat weak engine.

[Sea Skimmer]

Yeah, it's a macro scale on average thing. I was wondering about IC engines simply because I understand they are basically explosion powered engines and gasoline has a much higher energy density than gunpowder.

The internal function of gasoline and diesel piston engines is not an explosion, its a much smoother form of combustion meant to keep pace with the movement of the piston and maintain a near constant rather then rising pressure. When explosions occur this is called engine knock and that can reach the point of blowing the pistons apart if left unchecked. Modern engines, actually rather old engines, all have anti knock sensors to help avoid this by cutting fuel flow, and this is why using the proper octane of gasoline for an engine matters. If the octane is too low for the compression ratio it will burn too fast and turn into an explosion. The knock sensors are pretty simple devices based on shock, you can test one just by hitting the running engine with a hammer a few times and seeing if the power suddenly cuts down.

So I guess the question is that if you substituted an equal amount of gunpowder for fuel/air in the combustion chamber, would it still work? Yes, no, and yes but poorly can all lead to interesting and internally consistent technologies, which is really the goal in the end.

Gunpowder engines really existed in the 19th century, they sucked but they will work and I'm sure can be readily looked up on Google. Really bad idea, but in principle given a proper design anything that will burn and produce an expanded volume of gas in the process can make an internal combustion engine function. You couldn't just pour gunpowder into a gasoline engine and have it run though. Well, it might run for a very short period, before the values or piston rings started to come apart.

[Gunhead]

Have to ask, why have some magical thing preventing high explosives from working when you could just say they haven't been invented yet? After that you can just peg the mundane tech level to whatever you want it to be or push it down any sort of strange magictech mix you choose, which wouldn't be at all out of place if you take stuff from Spelljammer etc.

To echo Skimmer, I'm not too sure OP's limitation would rule out fully functional IC-engine. While blackpowder has significantly less stored energy than gasoline, from what I could find out it does release it quite a bit faster so IC-engines should work. Couldn't find a neat answer to this, it's all about the energy content vs. speed of burn and all it might cause is that your IC engines become really big with a ton of pistons firing in sequence instead of just a few like we have today.

-Gunhead

[madd0ct0r]

there you Darmius, a simple rule for your world:

Gunpowder is classified as a low explosive because of its relatively slow decomposition rate and consequently low brisance. Low explosives deflagrate (i.e., burn) at subsonic speeds, whereas high explosives detonate, producing a supersonic wave.

http://en.wikipedia.org/wiki/Gunpowder

Much of this depends on macro-scale arrangement. The same powder ground to a very fine powder goes bang very quickly while a coarser powder (like brown powder) spreads that energy out over time, resulting in a lower spike

Blackpowder can be used for quarrying and blasting, and, if modified to burn SLOWLY, it can run an internal combustion engine.
https://www.youtube.com/watch?v=oE29MJOnTdE

So there's just some sort of meta friction in your world that eats up the kinetic energy of anything that's supersonic.* Maybe the ether gets in the way It'd be a bit like how c is an absolute velocity in this world

* I have no idea how that'd handle stuff that's underwater, whether the speed is absolute or relative to the medium.

[LaCroix]

if deflagration is ok, gasoline engines are A-Ok for the world...

[Borgholio]

Yeah if he's simply referring to an explosive force such as dynamite or a bomb, then internal combustion will be fine, as would nuclear power and rocket fuel.

[Darmalus]

The reason it's being universally restricted instead of simply not invented is that the setting is part of a massive multidimensional setting my friends and I have been running games in since high school. Unlike in SDN versus debates, we have technologies frequently not work in other universes to keep things interesting instead of having a universal optimal solution. As I've gotten older I try to make the various rules have internally consistent results that flow naturally rather than arbitrarily (like I did in high school).

Thanks for the correction on IC engines, I've never worked on them so my mental model was very simple and clearly massively inaccurate.

I'll think and maybe tinker with the setting some more. I think I've fallen in love with the idea of nuclear powered land battleships and I want to make that happen if I can without breaking everything else.

[Venator]

To tiptoe around the topic of whether or not and how internal combustion works - what are mages capable of (and not) in the setting? You mentioned it takes a lot of effort to train one to battle-readiness, but could a mage levitate a tank if the combustion engine doesn't work, or create huge blasts of energy to shame blackpowder arms, or increase the efficiency of a steam engine to make steam tanks viably powerful?

My immediate thought when given a setting where all new technological advances in explosives are rendered meaningless by fiat, but they already have magic, was that they'd just start a magical arms race instead.

[biostem]

Would black powder be sufficient to, for instance, cycle a full auto assault rifle?

I mean, there are some pretty impressive things people came up with before electronics were a viable option...

[Beowulf]

The problem with black powder is fouling. Of course, there's no reason why you can't use something cleaner burning. It just won't give any more power. You'd probably end up with rather large caliber rounds to make up for the low velocity... It'd probably end up looking more like a submachinegun than an assault rifle.