Could the development of a body armour that completely stops any small arms fire make a civilization go back to medieval-style combat?

Question

In my futuristic narrative, nations at war have invented a fabric just a bit heavier than cloth, that effectively stops any small arms fire. This huge leap in technology made gunpowder-based small arms useless. Large calibre anti-vehicle guns are still effective because of their sheer power and explosive nature. Weapons like portable railguns (extremely high velocity) would punch through this armour and exist in this universe.

Here are some axes of reflection :

• Could these nations have gotten back to medieval style combat with swords, hammers, spears?
• Could an armour that stops small, high velocity projectiles be vulnerable against melee weapons?
• Could arrow-like projectiles (slow but heavier) still be able to pierce that armour?

I have heard that current soft body armour is not stab-proof and that crossbow bolts can easily punch through.

I am trying to make this as realistic and as plausible as possible. Since it's the future these weapons could have futuristic modifications, like reactors at the end of a hammer, chainsaw-like blades (the edge would be moving quickly along the length of the blade), bows which create a magnetic field that enhances the speed of the arrow or a mechanism in said arrow that could improve impact force or penetration.

These weapons have to remain ballistic based. I already have designed plasma and laser weapons to counter that armour. Bonus if you find a reason for these weapons to remain single-shot or too complicated to make them magazine-fed.

MORE PARTICULARS CONCERNING RANGED WEAPONS :

I am designing a game so these decisions are for game balance mainly. There should be 3 types of weapons :

• "Hitscan" weapons with great range but very slow rate of fire (railguns, single shots, "musket-like").
• Single shot weapons with an arc and travel time, with medium rate of fire (a bit like a crossbow).
• Single shot chargeable weapons with an arc and travel time, with higher rate of fire (a bit like a bow).

NOTE : I have made a separate question for those who want to discuss the armor itself here.

Answer 1

Could these nations have to come back to medieval style combat with swords, hammers, spears?

No, because staying far away from someone trying to kill you is always the better idea.

Could arrow-like projectiles (slowfast but heavier) still be able to pierce that armour?

It already does...

https://en.wikipedia.org/wiki/Armour-piercing_fin-stabilized_discarding_sabot (APFSDS) rounds pierce through the heaviest current armor.

But, you say, that's too big for infantry!

For that, you drop down to the https://en.wikipedia.org/wiki/Armour-piercing_discarding_sabot (APDS) round.

Armour-piercing discarding sabot (APDS) is a type of kinetic energy projectile fired from a rifled-barrel gun to attack armoured targets. APDS rounds are sabot rounds, firing a spin-stabilized armor penetrating sub-projectile

APDS rounds are still commonly used in small or medium calibre weapon systems.

Even smaller is the https://en.wikipedia.org/wiki/Saboted_light_armor_penetrator (SLAP)

The saboted light armor penetrator (SLAP) family of ammunition is designed to penetrate armor more efficiently than standard armor-piercing ammunition.

The SLAP design incorporates a polymer sabot, which allows for the use of a tungsten penetrator projectile of a lesser diameter than the original bore. By using the casing of a large cartridge with a lightweight projectile, the velocity of the projectile is greatly increased and the sectional density is improved.

Answer 2

No - melee weapons are not going to plausibly come back, no matter what armor you develop. A man will not be able to exert as much force with a warhammer as he would with a shotgun. If a shotgun cannot pierce the armor, a spear is just going to be laughed at.

The reason why some basic light armors can be pierced by stabbing with a knife (or by a crossbow bolt with a cutting head) but not light pistol ammo is that they work by kevlar fibers catching the bullet and distributing the force, but an edged projectile slices the fibers so the force is not dispersed over a larger area (though it still takes some energy to cut them). There are stab-proof vests which are made to resist stabbing - this is a matter of building the armor to meet whatever threat is expected, while keeping that to a minimum protection needed for the comfort of the wearer over long periods. There is no inherent superiority of cutting weapons over firearms.

I will point out that even with a supposedly bullet-proof vest, getting shot still does significant damage to the person wearing it - the force is spread out as blunt force trauma across a wider area, instead of a small round piercing through, but the same total force is still applied. These vests are only to stop pistol rounds - to stop rifle rounds, you need much heavier body armor which has steel or ceramic inserts (ceramic does a slightly better job in that the shattering of it dissipates some energy, but a cracked plate renders it useless). Even "stopping" the round transfers the energy into the body wearing the armor. Scale your armor up large enough, and you could get to the point where the armor remains completely unscathed... but the person inside it has been turned into goo by the impact.

Weapons adjust to their purpose. While the typical infantryman's rife currently fires relatively small lightweight rounds, this is because it currently suits their purpose (namely being light enough to carry more rounds on a march and still being sufficiently effective against unarmored opponents). Armor which somehow dissipates the energy of the round, would cause a shift to heavier rounds, or slightly different configuration/composition, to whatever would match the circumstances the soldiers are facing. If that means an army switches to shotguns firing some kind of flechette rounds, then that is what will happen. That is a quick and easy change which will happen far more rapidly than you can deploy new innovative armors.

In order for melee weapons to be superior, you would need the addition of some kind of powered exoskeleton to allow the soldier to exert far more force than the human body is capable of (both in terms of applying the energy but also resist just knocking themselves back when hitting you - the energy gets applied both ways). Your melee weapon power armor, which would have cost an enormous fortune to produce, not to mention the amount of training required for the soldier inside to be capable in it and the extensive logistics involved with maintenance and provisioning, would be defeated by an extremely cheap projectile weapon before he could even close distance to the enemy. If that means everyone carries a slightly heavier rifle with composite rounds designed for piercing your new armor, so be it. If that means most soldiers are carrying RPGs and only a few rounds, that is still a comparatively cheap and quick change, which defeats your extremely expensive armor at very low cost.

Answer 3

It sounds like what you're after is something akin to Dune-style forcefields that permit slow-moving objects to pass through them but prevent fast-moving ones.

If you're looking for something grounded in current physical knowledge and technologies then I'm not sure this will help you, but some sort of forcefield that deflects incoming projectiles proportional to their kinetic energy might result in what you're after. "The slow blade penetrates the shield".

You'd still need an in-universe-plausible reason people don't just get pulped by the force of the impact transferring through the shield. If you're in the realms of fantasy-technologies this far you might as well go the whole hog and have it convert the kinetic energy to electricity somehow so you get lightning arcing off your shields each time you're hit.

Answer 4

No, materials science is not going to suddenly favor low-energy weapons.

If you want to encourage such weapons, presume a semi-disinterested weakly godlike AI who decides that personal guns are no longer allowed.

Use a gun, and the AI makes it a bad idea. Maybe its drones kill you. Maybe its drones fire interceptor rounds. Maybe both.

The AI doesn't ban arrows, knives, hammers, etc. It doesn't ban laser weapons. It even doesn't ban human carried railguns. Non-human portable guns are also not banned.

Just human carried guns.

Possibly we ended up with a weakly godlike AI, and someone slipped in some anti-gun laws. After the deaths of millions during the enforcement action they managed to prevent people slipping in new laws by creating laws that ban creating other laws. Repealing the earlier laws proved impossible or dangerous, so it wasn't done.

Now humanity lives with arbitrary restrictions, but humans still like to kill each other, so they have adapted.

A weakly godlike AI is an AI that has capabilities we cannot match or oppose, but is unable to do almost arbitrary things from our perspective. So we cannot oppose it, nor can we understand it. No miracles, but has super science.

Answer 5

In my futuristic, nations at war have invented a fabric just a bit heavier than cloth, that effectively stops any small arms fire.

Since you asked for a reality check... this is not possible.

We currently have civilian small arms that can put a round through steel plates and concrete blocks. (To say nothing of military small arms that are classified as anti-materiel weapons, which are designed for use and against, and are effective against "light" armored vehicles.) You are simply not going to be able to create a light fabric that can sustain an impact with that much kinetic energy. And even if you could, you'd just succeed in changing what type of projectiles are fired from guns.

Currently, firearms generally rely on propelling a blunt projectile at high speeds to apply crushing force trauma to their intended target. Kevlar and similar materials are good at dissipating and defeating this type of force, but even so they have their limits - most armor piercing rounds work on the same fundamental principle (high speed crushing force trauma), just using harder materials and higher velocities. Of particular importance, though, is that these materials only hold up well against crushing force impacts, not, for example, sharp force impacts. You want to kill someone through a Kevlar vest, you can do that easily with a bow and arrow, for example.

So even if you manage to somehow create a fabric that blocks all crushing force trauma, rendering current bullet designs ineffective, you have the problem of dealing with sharp-force trauma. It would not be difficult to design projectiles to be razor-sharp at the tips, which would shred your fabric. More problematic is that simple crushing force or sharp force impact is hardly the end of the line for projectile weapons. We have incendiary rounds and explosive rounds for various small arms, and even have specialized small arms that can deliver chemical agents into a target. (Not firearms in the traditional sense, but there's no reason we couldn't do that, if some miracle fabric arrived on the scene that made it beneficial to put a chemical payload into a bullet.)

So bottom line, you can't do what you're proposing, realistically, and even if you could, you'd just succeed in changing what type of bullets are fired from guns. Ranged combat is just too much of advantage to give up. (There's even a theory that we humans owe our status as apex predators to our preference for ranged weaponry - other predators risk injury and death when engaging prey in melee combat, but our use of ranged weapons has largely eliminated that risk, at least as it relates to the food chain, so that behavior is so vastly beneficial, it's just not going to change.)

Answer 6

Looking at weapons evolution in our history, I dare answering NO.

Look at what happened with tanks: initially they could be pierced by "simple" projectiles, which led to the development of heavier armors.

This led to the development of more sophisticated shells, which again led to the development of reactive armors.

Something similar happens with bullet proof jackets: just shot a more energetic bullet.

Basically, the evolution of weapons and countermeasures is reciprocal chasing: nobody slows down or even goes back.

Answer 7

Assuming 100% protection for any small arms (Which is not a given for any realistic technologies we have today), there will still be areas which are left unprotected. Shoot somebody in the head, and it doesn't matter if they have a bullet proof vest on. Shoot them in the arms, and they can't fight. Shoot them in the legs and feet, and they won't advance on your position.

Not to mention, ramping up the velocity or weight of the bullet would render the protection moot. A 50 caliber round will penetrate 1/2 inch of steel. Even if the cloth stops the bullet, that much energy is going to hurt.

Answer 8

To answer your three main questions:

Could these nations have to come back to medieval style combat with swords, hammers, spears?

Probably not. While it would obviously change how people fight, it probably wouldn't result in a reversion to classical melee weapons being the preferred option. There's too much advantage to killing someone from a distance, and based on what you've said flamethrowers and other chemical dispersion weapons would probably still work.

Could an armour that stops small, high velocity projectiles be vulnerable against melee weapons?

Yes, most likely it would. In fact, modern military body-armor should in theory be very vulnerable to attacks with bludgeoning weapons like maces or warhammers, and most anti-ballistic vests can be cut pretty easily, but these facts are often not taken advantage of because it's much safer to engage a target who is equipped with a firearm from a distance than it is at close range.

Could arrow-like projectiles (slow but heavier) still be able to pierce that armour?

That depends on how the armor derives its invulnerability. In a realistic scenario using actual physics, faster projectiles penetrate better than slower ones under otherwise identical conditions. Velocity isn't everything though, and energy matters too (this is why .45 ACP, while much slower than 9x19mm, generally has better penetration, it's got about 20% more energy on impact than the 9x19mm).

With a 50 pound draw, you can expect a typical carbon-fiber arrow to be moving at about 110 m/s as it leaves the bow and carrying about 147 J of energy. That's not very fast, and it's a miniscule amount of energy (about 35 calories or about 40 milliwatt hours). Even the lowest power firearm loads have almost twice that velocity and generally about the same energy. A typical rifle cartridge (5.56x45, used in the M16 rifle and most NATO members' military rifles) has more than 8 times that velocity and more than 10 times the energy, and typical anti-materiel rifle cartridges (.50 BMG for example) travel almost 9 times as fast and carry more than 100 times the energy while still being portable enough to be considered 'light arms'.

Pretty much, unless you're doing some fancy materials science and creating armor that can only be penetrated using materials that can't tolerate the stress of being fired from a gun at high velocity, anything that can stop light arms fire is also going to stop arrows without much effort, and probably crossbow bolts too (which are much closer to the low-power firearm cartridges.

There are two other points to consider though regarding this final part of the question:

Other means of propelling a projectile reliably at low speed.

You've probably heard of BB guns, capguns, and airsoft guns. The first two are actually firearms (no matter what the US BATFE says). All three are capable of propelling small projectiles at speeds similar to an arrow, all of them are more reliable and easier to use than a bow, and all three are also more than capable of being lethal to humans if used right (you need damn good aim for that though, because you have to hit a critical part of the nervous system or the circulatory system and the part you hit can't be protected by bones). If you base your armor's abilities to deflect projectiles solely on speed, these will all get through it with no issue, and similarly basing properties on material that can only be damaged by some other material that's heat or velocity sensitive then these can probably get through it too.

On the note of railguns and coilguns.

There's a practical upper limit on how fast a railgun can get a projectile moving and still have it be at least slightly portable (resulting from a combination of issues with heat dissipation and energy consumption), and that limit using current technology is likely to be less than the speed and energy of a high-powered anti-materiel rifle (which would also be more portable). The few portable ones which have been made that used conventional projectiles also have fiendish recoil (as a matter of perspective, even a trained soldier can't safely handle the recoil from a .50 BMG rifle unless lying prone, and 20x102mm (the upper end for modern anti-materiel rifles) requires specialized recoil compensation to be safely usable even lying prone with the rifle braced properly, and any conventional railgun that can achieve the same results will have similar recoil (unless of course you decide to just eliminate Newton's third law, but if you do that you can also very easily make armor that behaves as you require).

Plasma railguns might work as an alternative (yes, those are a real thing) given that portable ones (usually small DIY projects) have rather low recoil, but they require even more energy than a conventional railgun (and if you can store that much energy portably, why not just convert your power cells to be used as grenades and be done with it?), and they have very low stopping power. A plasma railgun could be used as an incendiary weapon, but at that point it's still probably going to be inferior in terms of performance to high-explosive anti-tank rounds or more conventional incendiary rounds (especially when you consider white phosphorus and napalm as options), so you'd essentially need to handwave some special property of the armor that makes it weak to plasma weapons (perhaps something about the ionization properties)?

TL;DR

In short, short of some really complex physics we don't yet understand, this probably wouldn't work. Even accounting for that, it's not likely to result in the changes you suggest simply because things like guns are just too efficient compared to older technology.

Answer 9

Is the armor proof against energy weapons? Explosives? Being dropped from a height? If not, there are plenty of other ways to kill a person than shooting them.

Now, it's possible that blades may become more popular - Kevlar can be cut. But it's just as easy to move past a defense technologically than it is to find an old trick that works.

Answer 10

Assuming that this cloth armor is inexpensive and can stop bullets, it will still not bring back hand-to-hand combat.

First, the weapons you mention (chain-swords and such) would be more expensive than any distance weapons I can think of. They would also require much more skill to use than using a gun. And they'd be prone to a lot of breakdowns.

Second, as most of the answers before me have stated, the energy of the bullet has to go somewhere. Even if it stops the bullet, the kinetic energy will break bones. Instead of feeling like you've been hit with a bullet, you will feel like you've been hit with a huge mace.

That is the reality. However, I believe you are working on this for a game?

Just have higher technology destroyed or made useless somehow. For example the force fields that were used in Dune did have the ability to stop weapons above a certain speed. Even a knife had to be used slowly to penetrate the force field. However, the biggest effect the shields had on combat was that it took energy weapons out of the action. If a laser hit a force field it created two huge explosions (one at the shield and another at the laser). Lasers were more effective if the opponents didn't have lasers.

And shields could be overloaded with kinetic weapons. Soldiers just had to carry heavier weapons.

If your case the armies would probably adjust such that some soldiers would carry heavier automatic weapons on tripods, and others would carry smaller weapons designed to go through the armor by other means.

Also don't forget that very quickly both sides would have the same armor and if the armor is that good at stopping bullets, if would allow larger weapons to be used without worrying as much about the recoil.

War isn't what such an armor would change. What it would change is terrorism. Imagine terrorists that knew they'd be safe from the relatively small weapons of security personnel and police.

Just read the US papers today. There have been a huge number of mass shootings against civilians this year. Imagine that any of these idiots have protection against normal civilian weapons? At least until the civilians get better armed. And that way is more dangerous for everybody.

Answer 11

The scenario you paint in your question looks to me a bit like the introduction of full-plate armor in the medieval ages. A fully plate-enclosed knight is virtually immune to arrows and bolts, unless he gets very unlucky. However, the knight was still vulnerable to blunt force, hence the popularity of warhammers and maces.

Also today, we have Kevlar vests, which provide some protection against small arms fire. However, even if there was such a thing as full-Kevlar armor, the wearer would also be vulnerable to blunt force.

Could these nations have to come back to medieval style combat 
with swords, hammers, spears?

Melee weapons are definitely an option for stealthy, commando-style forces, as an incapacitating blow with a blunt instrument makes much less noise than a firearm. However, a complete reversal to medieval style combat seems unlikely, as firearms bring a lot of punch to the battle field, even if combattants are somehow protected.

Could an armour that stops small, high velocity projectiles be vulnerable 
against melee weapons?

Any flexible body armor, even medieval full plate, leaves the wearer vulnerable, to some degree, to blunt force, i.e. melee weapons could be used.

Arrows and bolts are projectiles the same way that firearm bullets are. The effectiveness of a projectile can be gauged by several factors, the projectile's energy (mass times velocity squared), the projectile's cross-section, and others.

Could arrow-like projectiles (slow but heavier) still be able to pierce 
that armour?

You do not necessarily need to pierce the armor to do damage to the wearer, as a projectile that doesn't penetrate the armor still exerts blunt force. However, in this aspect, firearms would still be superior, except for sneak-attacks, as a longbow or crossbow is generally more silent than a firearm.

Answer 12

I think about this a lot for similar reasons and I can tell you from the research I've poured in (too lazy to dig atm) that intermolecular bonds are weak. If you have magnetic, kinetic, thermal, light, gravitational, chemical, sonic, and electrical energy as sources of damage. And break kinetic into momentum transfer, piercing, and slashing. Slashing and piercing win in most scenarios (positing uber future tech). Every energy form has it's own issues to deal with. Gravitational is pretty be-all end-all. At current understanding gravitational would block most things and penetratingly damage most things.

(I'm going to break the following into simple sections, but realize bludgeoning could be seen as piercing with a large cross-section, etc.)

An example of extreme levels of kinetic spear/shield scenarios:

• You can distribute momentum evenly over the shield (every part of it is pushed evenly in the same direction):

  You have no gradient in force so you have no extra stresses so your armor won't break unless your own physical resistance would do so. (Death or invulnerable). The momentum transfer of a weapon not braced against the ground is going to be just as damaging for the same reasons to the wielder. Bracing and lowering losses from viscosity (achieving a higher terminal velocity) can bring the spear to the break even point with the shield, but bracing is all the shield needs to compete.

  If you have no major redistribution of momentum you have regular impact vs regular bludgeoning resistance. Which will largely breakdown into several categories, one of which will be momentum vs momentum.

On the other side of kinetic we have piercing and slashing:

• Piercing: angle of tip sets piercing ability. The quicker the cross section grows the harder it is to push through as you need to. Conversely the thinner the cross section the more fragile the needle but more importantly the less damage it will do. Breaking a single bond with an atom wide needle is almost the same as what random dislocations would do already.

• Slashing: angle of edge follows same logic as piercing. Except you're affecting multiple bonds in a line in an orderly fashion. You create a proto-fracture: force will tend to redirect to and widen this line of broken bonds. Also if you slash through the shield you're most likely effecting a lower count of bonds than a piercing or bludgeoning weapon might.

  For piercing, the shield will not care about your interaction in a large way. Unless the operation of the entire fabric revolves around the precise arrangements of intermolecular bonds or you stab multiple areas quickly. Slashing through the material completely is a simple enough feat because it's the bonds of the cloth vs the slash weapon. Presumably your cloth is not the same as your material with strongest intermolecular bonds (and lowest cross-section). If it is you're at a stalemate again.

Essentially what it boils down to is if you can pick properties/tech will-nilly then spear/shield match-ups are stalemates which is the same as saying the shield won. Figure out which energy areas the shield and spear belong to and stick to them.

Your cloth happens to fit EXACTLY what you want it to be. Braced weapons already exist and cloth is not rigid (your not using it as a bracing material) so essentially small arms are "useless" by the above argument since it never transfers enough momentum. And by the same argument large braced ones are effective. If bonds in cloth are relatively weak an extremely sharp melee weapon could still have effect. And if you're willing to trade the cloth back down to kevlar-vest levels of protection: then you're looking at something where a sledgehammer is still effective but small handguns are not as effective.

Answer 13

If you have found a way to dispense the energy of an incoming projectile then yes, it will bring back medieval style hand to hand fighting.

It all boils down to where the energy go.

Ways to dispense the energy:

1. Have super strong material, that has very strong inter molecular attraction. That reserve of energy then counter the incoming energy. The energies cancel each other.

2. Have material that can absorb the energy to make new material. Perhaps have new bonds, make new compounds whatever.

3. Have the energy absorbed to change state of matter. It takes lots of energy to convert ice into liquid water for example. You may have some exotic state of matter coming into play.

4. Have active defense. You need to power your armor for that obviously.

5. Find some way for energy to go side ways perfectly. Your future technology may use super conductors for example. Your soldiers necessarily fight keeping distance between them.

As long as the incoming energy is not affecting your body you are golden.

Answer 14

You'd probably see more fire based weapons, which may count as medieval. Your armor can be made of completely fantastic stuff that blocks all but the highest energy railgun bolts. But without making it a space-suit, it will provide little mitigation against flamethrowers & Molitov cocktails. So these weapons could become more prevalent.

Also, weapons that bind their feet together like some kind of whip, possibly w/ some kind of glue, could be more viable in place of small firearms.

Answer 15

I'm basically going to agree with many other answers that say "no" to the question of bows & arrows / crossbows making a comeback, but for a simple reason that I think everyone else glanced over:

You are correct that some kinds of armor perform better against high-energy projectiles and it's (in the loosest sense) "plausible" that your cloth will be easier to penetrate with lower energy projectiles. That having been said, its easier to make armor that performs well against low-energy projectiles than it is to make armor that performs against high energy projectiles. In your world, all people would have to do is use a bilayer armor to make both irrelevant. This is kind of already done when soldiers and the like use Kevlar with steel plating.

Now, I do think the melee weapon angle is a little more plausible than others have given it credit for, but not because of the speed/energy difference. Rather, melee weapons allow force to be continually applied. Now, you can't have people lining up with swords in a world where missiles, bombs, rail guns, conventional artillery and so on exist. That would be suicide. But, I could maybe see long knives and short swords (using better modern materials) be useful for assassinations and the like.

There is one other caveat though: You're fairly focused on projectiles. Explosives, chemical weapons, and biological weapons also all exist. In this world sonic and heat based weapons are also likely in vogue. Swords (or any other melee weapon, I'm just using them as an example) have stiff competition unless there's a cultural aspect.

Here's my suggestion: Swords (or, again, sub your favorite weapons) were used for duels long after firearms had made them mostly irrelevant on the battlefield. In my opinion, the reason for this is that, while they aren't your best battlefield tool, they were still kind of practical for one-on-one fights. Not to mention, they were still worth carrying in the days where you could only shoot once before reloading. You have a similar situation. They won't win battles, but they aren't useless. Maybe soldiers carry them for and for defending against small raiding parties that try to sneak in around the artillery. Once in close quarters, you won't want to use the other weapons that I mentioned since you'll kill your own people. Basically, they fill the role that bayonets did until the mid twentieth century.

Answer 16

No. As even if you can stop the projectile as long as this is a cloth, it will have no means to prevent the cloth from folding in & just following along with the bullet. Meaning you will still need to find another way to disperse the energy of the round using normal materials. (For this part i'm probably getting all the terminology wrong but hopefully the point will still get across) This issue in irl body armour is referred to as back face deformation. Where the bullet is stopped, but the materiel itself still deforms, putting meaning the use is still hit with a significant force in a small area. (someone please edit this bit if you know how to phrase that better)

And even if you fix this issue you still have the issue of the other guy being able to use a bigger gun, or more even small explosives. Making all this effort while not wasted (now they have to carry heavier shit) still negated.