What does it look like now?
Firstly, it’s important to understand the trade offs that go into the production of body armour. While there are dozens of factors, we can simplify it for our purposes to an axis with protection at one end and mobility at the other. The more protection the body armour provides the less mobility it allows (and the more it costs coincidentally).
There are two key kinds of armour in use today. ‘Soft’ or flexible armour made from materials like Kevlar or Twaron and the like, and ‘hard’ armour usually made from metal or ceramic composites.
You can make your weave tighter and treat it with a resin to make it less likely to split, but by doing this you are directly reducing the flexibility. So, while we can make a comfortable carbon fibre jacket that will protect you from all manner of slashing attacks and still allow arm movement, we cannot make one that will stop a rifle round and still give you moveable shoulder and elbow joints.
For these reasons most soft armour we make will stop knives, pistols and shotguns, but not rifle rounds. Accordingly, we issue such armour in the domestic space, to police and security who aren’t likely to encounter a lot of assault weapons.
The limitations of plates are also fairly evident, since this armour’s rigid, you can’t have plate protection over your joints. Going further, the stronger the round you want to stop, the heavier the plate; the heavier the plate the more it slows you down.
Hard plates are pretty much only used by the military and police tactical units. Not only is it too uncomfortable for ‘just in case’ use, but it also tends to be fairly tightly controlled. In most developed countries you’ll need a license to own even soft body armour, let alone something that will protect you from assault rifles.
The way weight affects mobility warrants a bit of expansion. If you take a 2.5kg steel plate and put in in a soldier’s chest harness, they’ll not be noticeably fatigued. On the other hand if you take the same weight in plating and put it on their boot or hand, they’ll fatigue very quickly as they move around. The further out from your core a weight is, the more difficult it is for a human to manage. Even a decent plate worn on the thigh will have a surprising impact on a soldier’s endurance.
For this reason, most battlefield outfits are just basic tear resistant fabric, sometimes with a bit of cushioning against impacts around the elbows, knees and such. The only protection from bullets is worn around the torso, head and sometimes the shoulders and groin. Certainly this means you can be hit in the leg, but if you’re wearing so much heavy armour that you’re too exhausted to move you will be hit, and hit often, and not just in the leg.
Overall it’s useful to remember that people wear body armour to save their lives as a last resort, not to turn them into a single man avatar of war. In planning your science fiction world it’s useful to consider what we could do now, but choose not to.
We could cover a soldier head to toe in armour that would protect them from rifle fire but we don’t. If we did, that soldier would be so slow as to be easily singled out and killed by an RPG or a vehicle mounted light cannon of some kind. On a battlefield full of powerful ranged weapons it is always better to be fast and sneaky, than it is to be bullet resistant.
Regardless of what we can do, current best practice is to give soldiers enough armour to potentially save their lives, without further imperilling that life by compromising their mobility.
Join us in the next part when we discuss some of the most common science fiction armour tropes and how what we’ve learned about armour today is likely to affect their development and use.