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The .50 BMG is a very powerful round with a lot of penetrating power. I want to survive it.

I did some research on my own, I'm just not sure how to combine these in a way to effectively stop a .50 BMG AP (black tip) round.

My research:

https://phys.org/news/2016-04-metallic-glass-secret-almostbut-quiteunstructured.html

http://www.projectrho.com/public_html/rocket/bodyarmor.php#id--Physical_Armor

https://en.wikipedia.org/wiki/Sorbothane

http://www.spacedaily.com/reports/Mantis_shrimp_inspires_next_generation_of_ultra_strong_materials_999.html

https://en.wikipedia.org/wiki/Metal_matrix_composite

https://en.wikipedia.org/wiki/Metal_foam#Composites

https://en.wikipedia.org/wiki/Impact_depth

As you can see it's a hot mess with everything thrown in the mix: shock absorbers, liquid armor, Liquid Ocelot, bulk metallic glasses, and some physics. I don't know which one would be best.

The armor plate should be:

  • As light as possible (invincibility needs both armor and speed)
  • Capable of stopping .50 BMG AP rounds
  • Capable of stopping them multiple times at the same location, if possible

Unobtainium:

  • Using the magic of nanomachines, you can build stuff up from the atomic level ( i.e: carbon nanotubes are fine)
  • For the time being, material, financial, and energy costs don't matter.
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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$
    – James
    Feb 8 '19 at 19:21
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    $\begingroup$ So why is this a world building question again? $\endgroup$
    – Mr.J
    Feb 9 '19 at 0:11
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    $\begingroup$ @Mr.J How many .50 cal resistant graphene armors have you seen in your life? $\endgroup$
    – Mephistopheles
    Feb 9 '19 at 8:04
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    $\begingroup$ @Mephistopheles none, but this does not tackle anything that is world building related, the best place to ask this question is either sci fci SE, or physics SE. $\endgroup$
    – Mr.J
    Feb 9 '19 at 8:11
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    $\begingroup$ @Mr.J This armor is a part of my setting, I just didn't want to bother you with unimportant fluff $\endgroup$
    – Mephistopheles
    Feb 9 '19 at 8:24
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Use ceramic plates just like Infantry body armor that can stop a 7.62 NATO round, but much thicker. This causes the weight of the ceramic to be excessive for any normal individual wearing it, which requires a robotic exoskeleton to help with the carrying part. Invest your money in battery technology for the exoskeleton, not "unobtanium". Make the ceramic plates easy to replace, since they do tend to crack. Infantry ones usually fit into a pocket in a nylon vest. You can completely encase a person in enough armor to stop anything up to a vehicle mounted weapon in this way (obviously if they are aiming a 30mm or an ATGM at you, you still have problems).

We have the technology today to make the armor, very sophisticated robotic exoskeletons, and the necessary electronic controls. We only lack a good power supply (which has to be quiet for it to be useful to infantry).

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    $\begingroup$ Lithium-Air Battery? $\endgroup$
    – Mephistopheles
    Feb 8 '19 at 19:59
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    $\begingroup$ Quiet and cold... the problem with today's retail batteries (who knows what the military can do?) is that they get hot when recharged or drawn upon too quickly, putting a big thermal bullseye on your body. $\endgroup$
    – Join JBH on Codidact
    Feb 8 '19 at 22:08
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    $\begingroup$ Heat doesn't strike me as an insurmountable issue, but weight might be. You don't want to end up in a "tyranny of the battery equation" situation where you're carrying more batteries so that you can carry your batteries... $\endgroup$
    – Cadence
    Feb 9 '19 at 0:36
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    $\begingroup$ Honestly, a very small internal combustion engine is a great solution except for the noise it makes. The heat can be dispersed in a way that doesn't give off much signature. Maybe something like a tiny rotary engine inside a baffled muffler housing that suppresses the sound and disperses the heat. $\endgroup$
    – JBiggs
    Feb 9 '19 at 22:32
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    $\begingroup$ The problem with active anti-missile countermeasures are that you tend to hit friendly units nearby with the stuff you use to kill the missile. Reactive armor has always been tough to mix with infantry, which is the use case here. Honestly though, anti-vehicle weapons are not made to target man-sized targets which are adept at climbing up on roofs, getting behind low walls, laying on their belly in the ditch, etc. Vehicles can't take cover nearly as well as infantry, and anything using an anti vehicle weapon won't be very agile itself. $\endgroup$
    – JBiggs
    Feb 16 '19 at 18:06
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Use Diamene: https://www.google.com/amp/s/www.graphene-info.com/new-graphene-material-called-diamene-switches-flexible-harder-diamond-upon-impact%3famp

It is light, malleable and wearable but once something hits it becomes extremely hard. Use a few hundred layers that are inlaid into a spidersilk-like substance as such substances are also light, malleable and extremely durable. This helps keep the fragments of Graphene (if there are some) to stay in place, since Graphene's edges are very sharp you dont want it to be flying about. The top layer being spidersilk also helps spread the impact a little before it reaches the Graphene.

To make the most of these layers, you first have the spidersilk at the top. Spidersilk is used instead of Kevlar because it's much stronger (1, 2, mentions it can be 10 times stronger than Kevlar, 520 MJ /M3). Then you have alternating layters of diamene and Carbon Nanotubes (https://en.wikipedia.org/wiki/Carbon_nanotube) with a last layer of spidersilk finishing it off again. These are thinner than spidersilk allowing more layers of diamene and they provide the same lightweight, flexibility, support and strength while seperating the diamene layers from each other. Better yet, the optimal size of a CNT can fit another CNT inside which is slightly less strong but it would add to the total strength. With a couple of hundred of these layers you are sure to stop several .50 BMG shots. Which leaves the kinetic energy to be disposed off:

You could augment this with non-newtonian fluids (https://en.m.wikipedia.org/wiki/Liquid_Armor), but in this case the fluids would only function as shock absorbers to reduce the kinetic impact before it reaches the body. But I would use a different method, mainly that of wheels. When a wheel hits something the metal frame is protected by the air in the rubber wheel (amongst other things). This impact causes an increase in pressure of the air and this is evenly divided over the wheel's frame. The armor would carry a liquid (probably an oil) that absorbs a lot of kinetic energy when it is pressurized. This is worn as a middle/bottom layer which rests on a frame. Whenever a bullet impacts the armour a portion of the energy is absorbed, turned into pressure and evenly divided over the frame so the pressure doesnt squeeze the user. It will never soak up the full kinetic force, but it will definitely spread the force even more than the other layers and absorb some to boot.

Edit: for those who say this cannot scale. It cannot scale by using 3+layers of graphene on top of each other. However if each Diamene layer is seperated from the rest they can all work like Diamene. A back of the envelope calculation using large CNT's to seperate each layer of Diamene you can fit 1763668 layers of seperated Diamene in 1 cm of armor. This defeats the claim that it would become too thick compared to current composite armors.

1: https://openi.nlm.nih.gov/detailedresult.php?img=PMC2939878_pone.0011234.g004&req=4 2: https://en.wikipedia.org/wiki/Darwin%27s_bark_spider

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  • $\begingroup$ It only works on two, though, no more, no less. $\endgroup$
    – Mephistopheles
    Feb 8 '19 at 20:45
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    $\begingroup$ @Mephistopheles Hence the "inlaid into a spidersilk-like substance" part. 1 layer of spider silk, 2 layers of Diamene, 1 more of silk, 2 more of Diamene, repeat a couple hundred times ... $\endgroup$
    – Dalila
    Feb 8 '19 at 21:08
  • $\begingroup$ @Mephistopheles Eh, since diamene is 2 atom layers thick and I mention you can use a FEW HUNDRED LAYERS, it would work on a few hundred shots, or maybe a dozen or so depending on how many it shatters with each impact. Personally rather than just Diamene layers with spider silk I would use one layer of Diamene, then a layer of CNT's to provide elasticity, strength and spread the force, then another layer. CNT's are thinner than spidersilk threads. $\endgroup$
    – Demigan
    Feb 8 '19 at 21:15
  • $\begingroup$ And why use spider silk? Kevlar is stronger, kevlar dipped into oobleck is the strongest. $\endgroup$
    – Mephistopheles
    Feb 8 '19 at 21:17
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    $\begingroup$ The problem is thickness, Diamine may be hard but it is so thin you can still push your finger through it, and it can't be made thicker. layering it does not actually help it since you need millions of layers, which results in massive bulk. its like having steel that can only exist as foil and gets really weak if it touches. $\endgroup$
    – John
    Feb 9 '19 at 3:51
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Futuristic material science and medieval suits of armor

Check out this article about nanotech-fabricated metal. Note this sentence: "A block of titanium where every atom was perfectly aligned with its neighbors would be ten times stronger than what can currently be produced."

You specifically mentioned this kind of nano-fabrication as a possibility. Well, it will work. Here's somebody shooting a titanium plate. It stops 50-cals. Even (just barely) an armor-piercing round.

People stopped wearing suits of armor because penetrating power simply grew too large. Armor would have had to be so thick it became impractically heavy.

But a block of metal with the same stopping power as the hunk in that video, that weighed a tenth as much? That's the same as being a tenth the thickness. That would be similar to the thickness of a suit of armor.

In other words, a suit of armor the thickness of an ordinary period-accurate piece could have the strength equivalent to a solid plate as thick as the plate in that video. And we know people used to wear old suits of armor; they trusted it with their lives.. Forging such a thing would require quite a lot of skill, but it could be done.

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    $\begingroup$ Guess I can go that route as well, though I'd still have to layer it, as every shot would fck over the atomic alignment and weaken the plates. $\endgroup$
    – Mephistopheles
    Feb 10 '19 at 16:01
  • $\begingroup$ @Mephistopheles: How about some sort of self-healing technology built in? Labs are just now beginning to produce materials that can do it. In your future, maybe they figured out how to do it with structurally-aligned titanium. $\endgroup$
    – J.D. Ray
    Feb 10 '19 at 16:50
  • $\begingroup$ Not a bad concept, but 50 BMG AP rounds pack almost 4 times as much kinetic energy as medieval mace which was used to kill without penetrating the armor. For this answer to work, you'd need to also solve for how to distribute the impact in such a way that it can not kill through your platemail. $\endgroup$
    – Nosajimiki
    Aug 14 '20 at 19:23
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The kinetic energy from the impact of a .50 BMG, particularly at close range, is huge. Use it. Per @Demigan's answer above, put in some mechanism to absorb the energy. But that energy will have to be dissipated or contained in some manner. Address @JBiggs concerns about battery life by using the energy to re-charge the batteries that help move the soldier around.

EDIT: The base of the armor kit should be an electrically-driven (e.g. motorized) “exoskeleton” (external to the human, internal to the armor), with power supplied by batteries. The armor plates should be mounted on actuators that re-direct the energy into a hydraulic fluid that is routed, via tubes (flexible at the joints) to a central hydrodynamic generator that turns the hydraulic energy into electricity. Movement in the armor, driven by the electric motors, would cause the hydrodynamic actuators to move, thus causing efficiency-sapping problems over time. Frequent re-charges of the batteries would overcome this, as would getting shot. It makes for an interesting problem space.

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    $\begingroup$ This is almost an answer, but not quite. It's more of a connecting comment to two other answers. Can you put a bit more time into this by explaining how to absorb, store, and reuse the energy of the bullet? $\endgroup$
    – Join JBH on Codidact
    Feb 8 '19 at 22:05
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I'll be as basic as I can. Ballistics Gel. You can make this stuff with common gelatin and it can stop a handgun bullet. I'm sure if you compacted it enough you would have something super effective.

Ballistic Gel (how to): https://www.instructables.com/id/Ballistic-Gel/

Ballistic Gel is known to DISPERSE the energy throughout itself. A bullet will sharply go through the gel at the beginning but then it will come to a complete stop.

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    $\begingroup$ You're basically suggesting me to use an artificial meatshield. I want powered armor and supersoldiers, not Lady Gaga. Besides, water cannot really be compressed further, and it'd still weigh a lot. $\endgroup$
    – Mephistopheles
    Feb 9 '19 at 20:08
  • $\begingroup$ This would be incredibly bulky for a soldier to wear. He'd probably have to have two foot thick slabs all around his body, and that would likely end up being so much gel that he would be too heavy to move. $\endgroup$
    – JBiggs
    Feb 9 '19 at 22:36
  • $\begingroup$ Also, dispersing the energy within itself doesn’t deal with the fact that the energy has to eventually go somewhere. If it’s dissipated as heat, fine, but how much heat is that? $\endgroup$
    – J.D. Ray
    Feb 10 '19 at 16:46
  • $\begingroup$ What about non-Newtonian fluids instead of ballistic gels which harden in response to impact? I still think there is a basic problem in the physics though. All the energy from a round that size and V has to go somewhere! Even if its stopped by some kind of advanced armor - inertia is always absorbed by the target. Standard ballistic vests stop pistol rounds no problem but the wearer still takes injuries - bruising, maybe a cracked rib or two. And trying to protect the limbs? .50 rounds have been demonstrated in combat to basically shear a human torso in two on impact. A limb would be severed. $\endgroup$
    – Mon
    Oct 3 '20 at 23:47
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In the absence of 'handwavium' SF technology like force fields etc there are simply unavoidable physical limits to how much 'wearable' physical armor you can place between a human being and an incoming physical projectile of a given mass/structure/velocity.

The point being that body armor doesn't 'magically' make the force of impact of a hit go away. All it does is distribute that inertia of the round across the immediate surface area of the piece of body armor concerned - without being physically destroyed in the process.

So yes you can design a piece of body armor using currently available materials that will stop a .50 round. What you won't be able to do is;

A) Make it light enough for a human being to carry and still remain combat effective; and

B) Prevent the human being wearing it from having to absorb the kinetic energy of the hit.

Forget Hollywood - taking a hit while wearing body armor, even from a run of the mill handgun round 'hurts' with a Capital H!

The energy of the bullet has to go somewhere and in this case its the human wearing the armor. So while you might be able to design a set of convention soft body armor with plates that could stop a .50 round I guarantee the human wearing it, while they might survive, wont be getting up and going dancing any time soon, let alone continue on fighting. (In fact they'll be in an intensive care ward.)

For that kind of resilience you are looking for you have to start taking about 'power armor' which is a level technology in the purely speculative realm at this point in time.

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A wearable version of a hard-kill active armor concept like Trophy used on armored vehicles would do it. The Russians claim their Kontakt active armor can stop high-velocity depleted uranium rounds, so that would do it.

You will also need some good Kevlar or equivalent because you're still going to get hit by a lot of fragments.

Dragonskin once claimed that their advanced concepts would stop .50 cal -- they used a series of overlapping ceramic scales. Hype or reality?

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