Speaker-Powered Directed Blast Weapon

Question

So, in order to defeat a bulletproof enemy that has genetically engineered osteodermic plates like a rhino all over his body that can stop very powerful rounds, the protagonist put her brains to work and decide to use a shockwave to turn his organs into mush from the inside, but grenades are messy because they blow in all directions and can cause unnecessary damage, so she develops a directed blast weapon, but how would this work?

At first, I thought about some sort of fragment-less-grenade-launcher that has a parabolic reflector at the tip, the grenade is timed to explode right at the focus point turning the blast into a beam of supersonic death.

But then I thought that it could instead use speakers powered by capacitors, though I'm not sure if a speaker could generate shockwaves, but then I could ditch the parabolic reflector and go for a slimmer parametric speaker composed of smaller ultrasonic speaker, maybe this would even solve the problem of a single speaker destroying itself from it's own blast.

Maybe I just wrote a bunch of nonsense that will piss off any physicist reading, if that's the case, I'd be glad to know what I got wrong.

Answer 1

Use HESH shells

You abandoned your first idea using explosives shockwaves too quickly. Sonic weapons have all sorts of limitations as already described in other answers, but High-Explosive Squash Head (HESH) shells are a special kind of explosive weapon that works on the principle you are trying to exploit.

So let's say you can not pierce the armor for what ever reason using a traditional penetrator or HEAT style shaped charge. HESH rounds work by sending a powerful shockwave through armor instead of trying to pernitrate it. They work by spreading thier explosive against the armor before detonating it. Between the squash effect and the shell casing acting to shape the blast, as much as 80% of the total energy from the blast can go directly into your target (much better than a messy grenade). This allows the explosive to transfer a maximum amount of energy into the armor rather than maximizing how small of a place you can hit like most other anti-tank weapons. Against normal tanks, they kill by spalling, but even if you armor plates don't spall, they will still be pressed up against the enemy's internal organs. This means that the energy of the impact will cause the plate itself to vibrate so violently that it will become like a giant speaker pressed directly against its insides destroying the internal organs.

In short: HESH shells would turn the armor plates themselves into sonic weapons.

Also, HESH shells scale down way better than many other types of high explosive anti-armor weapons because they are not totally reliant on thick metal internal components to shape the blast. Effective HESH munitions can be made using modified shoot-gun shells. Militaries world wide already own millions of 6-10 shot semi-automatic shotguns that could fire these weapons meaning it does not need to be some sort of rare and exoitic weapons system. Or if you need to go a bit larger, you could make them in 20-40mm varieties to be loaded into the RPG launchers commonly mounted on various military assault riffles already. Either way, it is MUCH easier to just manufacture a new kind of ammo than it is to invent and deploy a whole new weapon system. So instead of needing some specialty weapon only a handful of special ops groups might have, you could quickly put anti-rhino weapons in the hands of every single infantry task force who might need them.

Answer 2

Frame Challenge: Look up shaped armor piecing charges they've been around for more than a century and in widespread use since WW2. (See link below.) The principles are well understood and easy to engineer/implement. Without parameters on the size/mass etc of the target its hard to say how much of a charge would be needed but in theory, assuming a reasonably sized target (say bigger than a human but smaller than a horse) it might well be possible to engineer a suitably powerful shaped charge into large caliber rifle cartridges.

Shaped Charges

Answer 3

The problem with sound weapons is that they need to generate a wave and make sure that its still effective by the time it reaches its target.

To put it into perspective: if you want a soundwave as strong as a grenade to hit your target, you need to generate a sound that is essentially an explosive shockwave. Your speaker must be able to both generate and withstand that shockwave.

It gets worse, while you can direct a sound you cant make a sound laser, it will spread out. To make sure your sound hits like a grenade your speaker must create a pressure wave many many times stronger than that wave, which increases the farther you are from the target. And its not as if the weapon and wielder will receive nothing of that, as any action creates an equal and opposite reaction, meaning your protagonist is more likely to be jellyfied by her own weapon than the target.

At which point you are better off just launching grenades at your opponent. Either magnetically accelerated (your protagonist seems well able to make that kind of thing) or the more standard grenade launcher or Rocket Propelled Grenade launcher. I doubt it would be necessary to switch to shaped charges which have a pretty large minimum size.

Sound weapons are cool, if you want one you should get one. But its physically not a smart or very workable idea.

Answer 4

You can attack your metahuman using the principle of the brown note.

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

The brown note, also sometimes called the brown frequency or brown noise, is a hypothetical infrasonic frequency capable of causing fecal incontinence by creating acoustic resonance in the human bowel.

Ultrabass speakers mounted in the trunk of several (fine looking) cars approach your metahuman in reverse, all playing the same song together (they have Bluetooth speakers). Little does your metahuman know the bass line has been rigged and your cars can gradually adjust the frequency. His scales make his entire body an acoustic cavity. When they find the resonant frequency, hilarity ensues!

Answer 5

A few clarifications.

Grenades and bombs give a loud bang, but the way they damage stuff is not by sound. The shockwaves are from gases expanding violently, not from the sound of the explosion. If you want a blast, you want explosives, not sounds.

Sound weapons do exist and are used by armed forces and law enforcement. The technology most popular nowadays has existed since at least 2003 and is called LRAD. The sound "cannon" looks like this:

Source: the wiki I linked above.

It's the drum shaped thing that the guy in the picture is holding.

This doesn't "blast". It is used in two modes: it can either make a sound so loud you can hear it from three kilometers away (that's almost two miles, about 9,800 ft), or in crowd control mode you can just use it to cause discomfort to a lot of people that are in front of it. According to this article it can cause pain at 20 meters, and even hearing loss.

Of course, since you are going for the kill, you can start with this technology and fiddle with it to come up with something lethal. Take a page from nature too.

Sperm Whales are the loudest creatures on Earth. Depending on your sources, they can reach up to 230 decibels with their natural sonar. Some biologists suggest that their loud sound is weaponized in order to stun their prey, though last I checked there was no consensus on this. However, there is anecdotal evidence that a sperm whale's clicks can and will cause bodily harm on other creatures. Some people like swimming along the critters, and at least two guys have booped sperm whales on the nose.

James Nestor was being approached by an adult sperm whale and put in his hand to protect himself. He made contact, and his hand was paralyzed for four hours. He detailed his experience in his book Deep. His colleague Fabrice Schnöller also touched the nose of a calf, and similarly got his hand paralyzed. If you look at Youtube videos where they describe their experience, you see them talking about a feeling of your whole body vibrating and even heating up. Notice that while sperm whales have had violent contact with humans in the past, there has never been any report of them actually attacking humans with sound (only headbutting ships). It may either be that the whales are either incapable of causing further harm this way, or that touched Nestor and Schnöller were actually being "gentle" and could potentially have killed the divers with sound if provoked and willing.

Back to your weapon. Take the whale clicks up a notch, and you can use ultrassound to cook your victim from the inside. But you will probably need a sperm whale head sized speaker.

Answer 6

You could make a really powerful sound system and it could serve as a weapon against a target that (for plot reasons) is immune to other forms of attack, or especially vulnerable to sound for other plot reasons.

I think the main engineering challenge is actually to make it so that the speakers themselves can survive their own sound, and don't wreck themselves before they properly get started. This can be dealt with in several ways, for example a large number of speakers could all produce a less-than-self-destructive amount of noise, and then they could all be focussed so that the sound all constructively interferes at the target. Or if its easier for your story just handwaving some super-speakers.

Answer 7

Resonant frequency of the brain

Let's talk about the difference between sound and explosives. Both of them are shock waves, but sound is an oscillation of shock waves, whereas something that we call an explosion literally pushes away everything that might oscillate at speeds greater than the speed of sound.

With sound, there are two ways to inject more energy. The first is to add more volume, but that maxes out at 194 decibels, where the difference between the compression and the decompression is 2 atmospheres. The other way is to increase the speed of oscillations, but high frequency oscillations don't propagate through air very well.

What you're probably want is something that finds the resonant frequency of whatever you want to destroy. If you're talking about shooting human, then you want to go for the vulnerable parts. The resonant frequency of the human skull is around 22.3 Hz, and 13.9 Hz for the brain within. That should provide you with a weapon that turns the person's brain to mush, regardless of what armor he's wearing.

Now that you have the sound, how do you just hit the one person with it? For that you need directional speakers. This uses high-frequency sound waves that create interference patterns when they hit you, simulating specific frequencies. They're pretty cool. Whether or not you could pump enough sound through one of these to hurt someone is a question of science fiction.