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Comment by AnonMO | Hacker News Reader

My comment wasn’t this serious but I don’t think any munition that can damage an aircraft carrier will be that cheap. Also im no expert but with more energy isnt the distance at which the heat from the laser remains effective becomes longer right? So if the tech is truly mature isn’t 20km a bit naïve also what if each laser system is an array of lasers with independent movement maybe 10-20 laser per system this configuration will definitely out power drones at the scale you speak of. The future is hard to predict.

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> any munition that can damage an aircraft carrier will be that cheap

It's all about targeting smarts and precision! This has been well demonstrated in Ukraine, where GPS-guided missile artillery can simply "reach out and touch someone" 50 miles away.

Even tiny drones could do fantastic damage if precisely targetted using on-board AI. They could target personnel, fuel, electrical equipment, optics.

Don't think about a 50kg bomb dropped on the deck. Think of a swarm of 500g drones with 100g shaped charges making a beeline for the control tower, and the engine intake of every parked plane.

> "a swarm of 500g drones"

Which have laughable range and can't handle anything heavier than a stiff breeze, let alone weather conditions at sea.

There is probably a place for hydrogen filled (electrolysis[1]?) blimp drones[0], although needs height since blimps are slow and large targets, so perhaps fixed wing always more useful. Deploy when wind is favourable?

[0] https://m.youtube.com/watch?v=hMCqXmzzWFA

[1] https://www.chem.gla.ac.uk/cronin/images/pubs/Chisholm-Chapt...

Think of them as smart cluster bombs. A ballistic missile warhead could release a cloud of these things kilometers above a ship. They could drop passively and power up just a few tens of meters above the target.

If you don't think drones of the future will be the most horrifyingly effective weapons of war, you lack imagination.

Pack them in a torpedo that releases them right next to the boat.

Surely you are joking. If a hostile can get a torpedo that close to the target without being detected, they would just use a ordinary torpedo and warhead instead.

Maybe the ordinary torpedo with a warhead is too large and visible on radar. The drone torpedo could be much smaller, maybe the size of a common fish in the area. Maybe you have a bunch of them herded together traveling under water in the same manner as a school of fish might appear on radar.

Torpedoes aren't visible on radar, you mean sonar.

You're not going to sink a ship with 500g explosive fish-shaped torpedo-launched drone things. This plan boils down to a really weird and elaborate method of throwing hand grenades at a super-carrier until it sinks. This whole line of discussion is absurd.

What good is a carrier where half the crew is dead or dying, and every plane onboard has had a hole blown through the core of its jet engine?

... and is on fire?

I think that beyond 20km the horizon is between the laser and the drone. Maybe aircraft-mounted lasers could defend the carrier over a wider area.

If each drone costs US$50 then you can launch 180 million drones for the cost of an aircraft carrier. I don't think increasing the number of lasers from my 5 to 10-20 is going to help much.

I don't know what is needed for a munition to damage an aircraft carrier, but I feel like once it's on the deck it's already past the strong defenses and into the soft targets. It could be as simple as a wheeled robot that runs around stabbing random people, or a poison gas canister that fills the interior of the ship with mustard gas, or hundreds of hand-grenade-sized mini-claymores that deploy to random parts of the ship and conceal themselves quietly until a sailor happens to walk by.

> If each drone costs US$50 then you can launch 180 million drones for the cost of an aircraft carrier.

In a world of frictionless pulleys and spherical cows yes, in the real world, no. In the real world aircraft carriers and their attendant battle groups do not just park within visible range of a coast. Your drone swarm needs to find the carrier's battle group, get within launch range for your $50 drones (without being shot down), maintain some sort of identification of the carrier (or whatever ship), and then make a terminal approach.

A carrier's air group maintains a perimeter hundreds of miles away from the carrier group. Not just fighters flying CAP but AWACS planes keeping track of the airspace. No one is going to hide a million drones launching towards a carrier group. It would be unlikely hide even a hundred drones. A drone carrier large enough to launch a non-trivial number of suicide drones is also unlikely to go undetected.

Even if everything went right and someone managed to damage an aircraft carrier with a drone swarm, the carrier group alone has enough land attack weaponry to seriously hurt the source in retaliation. A nuclear response to an attack of a US carrier would not be outside the realm of possibility either.

Attacking a US carrier group is a really dumb idea even if you've got a really clever weapon.

You don't have to hide the million drones if the carrier group doesn't have enough firepower to destroy them all before they reach the carrier.

But you might be able to, if they're small enough. Or underwater.

If you can provoke nuclear retaliation, you win twice, at least to the extent that anyone can "win" a battle nowadays: first, you sink Enemy A's carrier (or, more realistically, permanently incapacitate it), and second, you draw Enemy A's nukes onto Enemy B's territory where you launched the drones from.

Shaped charges can blast a sizable hole through any material, likely big enough to fly the next drone through. Only so many hits to get through a hull.

Yeah, in a realistic scenario, if the carrier can take out 360 drones before the drone wave reaches it, the adversary would launch 700 drones, not 361. I hadn't even thought about hitting the carrier in the same place over and over again. But supposedly carriers aren't even designed with thick armor?

Nope, ain't that thick (< 1 inch). Probably built with multiple expendable flood chambers though, so swarm would likely need to make its way through the first hole. Plausible a single shaped charge does enough damage, but more likely some single-digit of hits needed.

Swimming + flying cheap drones doable: https://www.youtube.com/watch?v=FC9EJhs0pc0&ab_channel=Rutge...

At (wild overestimate) $1k per drone an attacker can wield 13 million drones for the equivalent cost of an aircraft carrier, not including ongoing expenses.

The sort of shaped charge you could put on a thousand dollar missile could probably pierce small holes in the hull of a ship (too small to fly anything through, that is fantasy. Shaped charges are bigger than the holes they make.) But even hundreds of holes like that that wouldn't sink a ship. Not least because the ship is filled with sailors trained in damage control, and that sort of damage wouldn't be particularly hard to patch up.

Clearing the flight deck with antipersonnel warheads would probably work better, but I wouldn't count on that to keep a carrier out of action for very long. If you really want to sink a ship, either use proper anti-ship warheads or don't bother trying.

If drones are so magically cheap, the carrier deploys its own magically cheap defensive drone swarm to protect itself when attacked by drones and remains unscathed.

Yeah, that's the future I'm pointing to: the aircraft carrier itself is no longer militarily relevant, because what counts are the drone swarms.

But there's no particular reason to expect that this future will be a Mohist one in which peace is ensured because magically cheap defensive drone swarms make every fortress impregnable and thus combatants' home territories always remain unscathed; at least as likely is a Second Variety future in which drone swarms are more effective for attack than for defense, perhaps even after all the human combatants are dead.

Would expect this to be the dominant countermeasure in the case where drones are a significant threat, yeah.

Though actually I'm coming around to the idea that a bunch of AI-targeted flak guns are sufficient, and that carriers are probably fine either way due to how close a series of missiles containing the swarm would have to get anyway.

What if a defensive drone swarm, to be effective, must be generations more advanced than the attacking drone swarm?

There could be an interim period of many years where very important stuff is very vulnerable.

Imagine you had a drone that could dive to the ocean floor, pick up a chunk of rock, fly up one foot above the deck and drop the rock, then fly back down and repeat. Imagine you had 10 thousand of these swarming a single aircraft carrier. You'd be able to sink it before long, and the poor sailors aboard will have no defence against 10 thousand tiny machines that only appear for a second and are all around the ship. Anything you fire at them is liable to damage the ship itself.

Maybe you wouldn't even need to have them come above the water line. Maybe the drone is just a weight and a magnet that can clamp onto the ships haul below the water line. Again, you can't combat that without having thousands of divers below your ship scraping the hull.

If someone had the technology to make a drone able to dive 3.7km to the bottom of the ocean, had enough strength to bring back a rock and then propel itself 40m above the surface and keep that small, your scenario would be the least of my worry.

Anyway, if you are in position to bring something close to a carrier from underwater, an heavy torpedo will do the job for a lot less money that your swarm.

As long as we're imagining we could use that same amount of energy and drop tungsten rods from orbit.

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

You clearly haven't done the relevant calculations.

Imagine you had a drone that could dive to the ocean floor, pick up a chunk of rock, fly up one foot above the deck and drop the rock, then fly back down and repeat

That would take a ridiculous amount of energy.

If we suppose we have to stack 100'000 more tonnes of rock on top of a 100'000 tonne displacement aircraft carrier to sink it, and the ocean is 2 km deep at that point, it takes about 1.96 terajoules at 100% efficiency. At 46 MJ/kg that's 43 tonnes of gasoline. That is a ridiculously small amount of energy to sink a carrier; it's maybe a large gas station.

Of course the question is open: how efficient would the rock-stacking drones be? If they're 50% efficient the scale of the operation is different than if they're 0.05% efficient.

Seems that energy will need to be expended in both directions, given that you're working in the opposite direction of the usual diving practice where a weighted diver sinks to the bottom and releases ballast to come back up. Is that being accounted for?

Also, I imagine somebody will notice this rock-stacking activity at some point over the (days? weeks?) it will to swamp the aircraft carrier, and take care of the problem with plain old birdshot. Or just a bunch of sailors with brooms or fire hoses.

Failing that, just cruise away from the drone swarm. They'll run out of gas long before the carrier runs out of U235.

It's easier to change your buoyancy by releasing ballast, but that's not the only option, or the best option in this context. You can instead adiabatically expand a vacuum space (for example, in a cylinder with a piston) against water pressure to go from negative to positive buoyancy.

100'000 tonnes is 100 million kg, so for a million drones it would be 100 dives.

I agree that stacking rocks on the deck of a carrier, or even gluing or magnet-clamping them to its hull, is probably not the most effective way for drones to damage it. Firing birdshot at sailors, for example, would be more effective; blinding them with lasers more effective still. The point is that even ridiculously primitive attacks become effective when you multiply them by enough orders of magnitude.

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