Hacker News Reader

Comment by baron816 | Hacker News Reader

I’ve been thinking: drone subs that could sit at the bottom of the ocean and then surface to fire anti-ship missiles. Essentially this https://youtu.be/hMBICD5rgY0?si=IXalKjfvs0pSL5B6

Imagine launching hundreds of these from the US or Japan and then they just camp at the bottom of the East China Sea. If tensions escalate, they can migrate towards the Taiwan Strait. And then, emerge potentially just hundreds of meters away from corvettes and landing vessels, fire off their missiles and then submerge.

View on HN

Why do you want to fire missiles if you have the technology to basically manufacture hundred of autonomous torpedos?

Would be much more efficient to just detect the ship from the bottom and then go explode under it. Torpedos do much more damage than missiles.

Navy thought the same thing. And they already have this (e.g., mine that has a torpedo).

I've always felt like I was missing something obvious for why there weren't submarine-launched SAMs or ASMs.

Seems like a really good way to target AWACS/tankers and valuable softer shipping, provided you have missiles with active guidance and can deploy launch pods under the sea, scoot, and then they launch when you've left the area.

Granted, much harder to do before networked unified sensors, but not nowadays.

> deploy launch pods under the sea, scoot, and then they launch when you've left the area

There are multiple dealbreaker for this: a) the launch pods need to be quite large in order to contain missiles and the surrounding infrastructure, probably including buoyancy control etc, b) submarines are veery slow so they need a long time to leave the area, c) the pods need to hang out near the surface to receive signals and to launch missiles, so they have a high risk of being detected before they can be used

It's probably more feasible to consider unmanned "disposable" submarines that can fire missiles. Still you have the problem of low speed and tricky communications though.

> the pods need to hang out near the surface to receive signals and to launch missiles, so they have a high risk of being detected before they can be used

You can now send encoded sonar pulses. With good microphones on pods, you can communicate over many many kilometers and those commands can be pretty short, no need to "real time fpv", just "target a ship currently at {X,Y}".

> the pods need to hang out near the surface to receive signals and to launch missiles

I'd think you could do some variation on attaching a long fiber optic filament to a fishing bob that has just enough electronics.

If you want to launch a SAM from a sub you first need to find whatever it is you want to shoot at. And if you radiate you're dead, you're limited to passive detection. And you have to stick something up to do that with--and the AWACS can see you from much farther away than you can see it.

The one thing that strikes me as a realistic threat would be to put up only a tiny antenna that can detect the radar of the AWACS. If you think it's in range you fire something like the AIM-120 on the line of bearing, radiation-seeking and then switch to it's active seeker when the target goes dark (as it almost certainly will if it thinks there's a radiation-homer out there.) They are slow, lumbering beasts that probably can't get out of acquisition range before the seeker goes active.

You still have the problem that you just left a flaming streak pointed right at you, a suicide move if you're anywhere near the fleet. It would make deploying an AWACS far from the fleet a bad idea, though. (Back with the old Harpoon wargame I found by far the best strategy was to station an AWACS a few hundred miles from the fleet in the general direction of the enemy. Russia had nothing with air-to-air weapons and the legs to engage it. It wouldn't be as effective against a competent enemy but it would still take a big bite out of maximum range by forcing the attackers to take a big detour around it.)

I also wonder how well an AWACS might be able to defend itself with it's radar. What happens to the seeker if the AWACS focuses it's radar on the missile?

Locate AWACS from ground/air/space sensors. (they're radiating like hell)

Communicate target location to sub via low-freq.

Sub transits to location. (realistically, would already need to be nearby)

Sub deploys canister. (have ICBM-dimensions to work with)

Canister hangs out just under surface, with surface communications buoy. Registers itself onto the fires network with LPI comms. ("I'm at XY cords w/ Z weapon", ACK)

Other assets then send order to fire when appropriate, w/ sufficient track. (since weapon is active, it just needs navigational track before it goes active)

Ideally, it's IR-guided, so AWACS doesn't get any lock warning.

Given SLBMs can toss a nuclear warhead at range, I expect they'd at least be able to loft several LREW / AIM-174 / AIM-260 class weapons to engagement altitude/speed. (~130,000 lbs vs 2,000 lbs)

ASMs would not be very useful. First submarines have piss poor detection capability outside of their sonar which severely limits the range at which they could launch them. Then they already have torpedoes which are effective against ships and can be guided from the range at which a submarine would be likely to want to fire.

SAMs have been considered mostly to fight against their natural enemy: the helicopters but I don’t think it has ever been actually fielded.

The issue remains the same in both case. Submarines are slow and firing is loud and basically broadcast your position to everyone.

There's exploration of integrating hypersonics with antiship strike capability on subs. But the TLDR is until PLA's massive A2D2 expansion to 1IC and beyond (1500km+), there aren't any adversaries that can prevent carrier groups from operating permissively - USN CSG airwing had standoff advantage against everyone. Hence (IMO) little reason (without consider technical stuff like extending kill chain to underwater - subs would need to get target queuing from above water sensors) to integrate SAMs/ASMs into subs, because as expensive as carriers are, subs are even more expensive per unit of fire/tube/vls. Extrapolate from Zumwalt hypersonic retrofit projections current 80 cells for TLAM (tomahawks) whittles down to ~12 CGHBs (common hypersonic glide bodies) to a SSN (~20 shots) and all of a sudden it costs 100-200m+ per shot on a 2-4B Ohio class. Extrapolate to SSNX @6-8B and cost ratio per shot gets even more ridiculous.

A version of this already exists (for awhile). It is a mine that sits at the bottom of the ocean and then launches a torpedo.

Reply on news.ycombinator.com