Like how do they work? like please explain it to me
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It’s just a pyrotechnic mix in a can. A firework in the shape of a grenade, if you’d like. An oxidizer (like potassium nitrate) and a metal like aluminum in powder form. Reacts violently, producing huge amounts of sound and light. Enough to cause you to be stunned to the ground through sheer sensory overload, without hurting you. Although you’re not exactly safe from a ruptured eardrum.
It’s just a small explosive with some aluminum packed around it in the right spot. The explosive is a fast burn rather than slow (relative for explosives), so it has a loud bang. The explosion heats and burns the aluminum which burns really bright.
It’s not like the videogames. Just like a big firecracker, if you hold one in your hand when it detonates, you’re gonna have a bad time. Don’t play around with them thinking “it’s safe since it’s not a grenade”.
They are basically grenades without shrapnel. A grenade produces a tiny explosion, which means heat, a wave of high pressure air, and very loud noise. These alone dissipate very quickly, meaning even if you’re just a few feet away you won’t be burned to death, blown to bits, or smooshed by air pressure to death from a grenade. What will kill you in a grenade is that they are designed to breakdown into tiny sharp fragments that fly out and hit you, basically shooting you with thousands of tiny bullets at once, so you’ll typically bleed to death.
A flash bang has all of that only it’s less powerful of an explosion and it’s design to not break into tiny bits.
So you still get this flash of light, a very loud sound, a large wave of air pressure that slams into you, the effect is magnified if your in a small room or hallway.
So again, assuming you’re a few feet away from the explosion, you’re not really going to get lethal injuries, you’re just going to be blinded, deafened, and seriously disoriented by the light/noise/air pressure wave. You’ll probably recover in a few minutes but you’ve probably been killed by soldiers long before that.
Of course, I’m not saying they are harmless, being very close to the explosion could still injure you severely and the wave of air can cause permanent hearing or body damage. Again, you’re probably already dead so tinnitus isn’t on your list of concerns at the moment.
A flashbang does just that: It makes a flash and a bang. Usually this is done by burning a metal powder such as magnesium or aluminum mixed with a solid oxidizer. As the metal burns it produces a lot of light and a rapid expansion of gasses which is allowed to escape the grenade housing as a loud bang sound (a fragmentation grenade would trap the expanding gasses until they caused the housing to explode, throwing deadly fragments).
The bright flash will overwhelm the eyes causing temporary blindness, and the loud sound can cause temporary deafness and even disturb the inner ear and impact balance. Overall most people find flashbangs very disorienting and they can give attackers an advantage in a crucial moment.
A normal grenade works by rapidly converting solid chemical explosive into very hot gas, which is many orders of magnitude less dense than the solid. The gas wants to take up a lot less room than the solid, so it attempts to expand. The case of the grenade is very solid, though, and doesn’t want to allow the gas to expand – until it does, catastrophically. The container is made of a thick, brittle metal that doesn’t bend, it just breaks like glass. The metal shatters into lots of tiny shards that get flung out in all directions with the force of bullets, and anyone caught in that hail of sharp metal has a bad day.
Many people are surprised by real grenades compared to Hollywood grenades, because real grenades have very little smoke and essentially no fire. Fire means that the chemical is changing slowly, burning in a big slow ball instead of going from solid to gas in fractions of a second. And, fire is wasting energy as light. A grenade wants to spend as much energy as possible pushing out on the metal container, and light doesn’t do that very well. Plus, if it’s light that you can see it means the light is happening *after* the container has already ruptured, which again means that energy isn’t being spent to create dangerous shrapnel. Grenades don’t really *burn* in the conventional sense.
Flashbangs do the opposite of most of that. The container is comparatively weak and designed to burst more like a balloon, bowing and bending instead of shattering. There’s even a metal shroud to help stop any metal bits from flying off to hurt someone. The chemical is designed to burn a little more slowly, and the chemical reaction is carefully tuned to create as much bright light as possible, typically using a metal like magnesium or aluminum that will burn very brightly. The flashbang is still designed to burn *quickly* and create a very bright flash as opposed to a slow, less bright burn, though. Also, when the container bursts it creates a very loud sound, like popping a balloon. A normal grenade does that, too, but the metal container absorbs a ton of that pressure as the metal becomes shrapnel. And, if you’re that close to a grenade you have more important things to worry about than the noise.
Flashbangs are used to disorient people. The light-sensing cells in your eyes have a sort of reset time before they are able to fire again. This is why looking at a bright light for a little while leaves a dark spot in your vision. More light means more cells fire and then have to reset. After such a bright flash, you’ll have some trouble seeing clearly for a few moments – long enough for soldiers or law enforcement to rush in and subdue you while you can’t aim well.
The loud bang does similar things to your ears. Your eardrum has muscles around it that can tighten the eardrum, making it stiff and unable to move as much. That limits how much energy can be sent back to the more delicate parts of your middle and inner ear, protecting them from damage. After the loud bang of the flashbang, your ears reflexively stiffen your eardrums to protect you, but this makes your hearing a little bit muffled, making communication and coordination more difficult – especially when there is probably a lot of other loud noises.
The worst part, though, is that the powerful pressure wave blasting through your ears can disrupt the liquid in your semi-circular canals which do the bulk of the work for helping you balance. As you move, gravity pulls the liquid down and your ears can sense where the liquid is and thus how your head is oriented relative to the ground. Mess that up with a good knock to the head and your balance gets thrown off. Your brain also uses information from your eyes to help you balance, mostly by looking for the horizon which you know is generally going to run horizontally through your field of vision. Your brain uses what you see to verify the information coming from your ears.
Except, your vision isn’t working so great after the flashbang, either. Suddenly, your balance isn’t working so great from your ears, you have no visual reference to use to fix it, and on top of that you can’t see what’s happening around you, you can’t *hear* what’s happening around you or what anyone else is doing, there’s probably some smoke, *and* if you were trying to pay attention to a particular entrance like a door or window you probably got very distracted by the very bright, very noisy thing and looked away from the entrance you were guarding. That’s a *lot* of distractions going on and your brain gets overloaded trying to figure out what’s going on or even remember what’s *supposed* to be going on, what you’re supposed to be doing, how to aim a weapon, *where* to aim a weapon, and then while all of that is happening there is a group of soldiers or LEOs running at you, tackling you, yelling at you, and maybe shooting at you.
Flashbang is the colloquial name, they technical term is noise flash distraction device or NFDD for short.
The ones saying it is a pyrotechnic mix are spot on. It’s something like photoflash powder that makes the bang and the effect.
There’s more to the entire construction.
There is a percussion primer like on a regular grenade. Once you remove the pin and let the handle go, the percussion primer gets hit by a spring loaded mechanism.
The primer is connected to a pyrotechnic delay: a composition that burns in a set time. That’s what gives you time to throw it.
The delay then will ignite the composition in the flashbang. The body of the device has vent holes (ideally venting from top and bottom so if you are still somehow holding it when it goes, it doesn’t injure your hand). The composition generates pressure and disperses metal particles. The pressure rise causes a bang and the metal particles burning in the air generate the flash.
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