Comment by gattr | Hacker News Reader

Comment by gattr | Hacker News Reader

A bit off-topic, but maybe some experts could answer a question?

I've recently re-read Clancy's "Red Storm Rising", the sections on submarine (and anti-) warfare are really interesting (I understand some of it may be simplified/fictional). E.g., how the Mark 48 torpedo can be set to and launched in "hunting mode", where it circles at a slow, undetectable speed, and only after acquiring a target it suddenly accelerates for a kill.

Let's consider this excerpt from [1]:

Terminal Homing is the final stage of the torpedo attack. (...) Terminal homing is an active sonar ping that retransmits on reception becoming more rapid as the range to target closes at maximum speed. (...) The target is alerted to the attack, but there is nothing it can do to defeat the weapon at this point. The weapon is too close and moving too fast to allow time for a countermeasure to be effective.

Now, I might have read too much David Weber ([2]), but wouldn't a small, cheap-ish counter-torpedo suffice? Put 10-20 of them in small automated launchers all around the hull, and let them crash head-on with the (now perfectly detectable) approaching boat-killer, still at a safe distance (which is.. I don't know, 100-200 m?)

[1] https://www.thedrive.com/the-war-zone/33018/modern-submarine...

[2] https://en.wikipedia.org/wiki/Honorverse

Kind of a sword vs shield thing as most things in the military.

There are sonar decoys. They aren't easy.

You also have to have it rigged ready to go with very little notice.

The other aspect is that these torpedoes can still be wired to the ship so you can continue to use the host sub's arguably better passive sonar systems and let the attacking torpedo get VERY close.

As with all things in submersible conflict the first person to be heard is dead.

The other aspect of your decoy system that you might not be thinking about is that you've a) compromised the hull with holes b) you are going to make a LOT of noise firing those off c) your sonar signature might go up dramatically when the doors are opened etc.

The hull actually has something similar to stealth coating (but for sonar, so easier to develop cuz it's against sound waves) on the hull. You really don't want to mess with it too much.

Sub warfare is insane. There isn't really a strong counter to them in the open ocean. USN Carrier groups are especially vulnerable (at least from exercises I've read about).

Your idea isn't bad. Just make it a towed array that pops off a bunch of really loud shit 1000m behind you or something.

This would eventually turn into a cat/mouse game of who can make a better system for detecting decoys vs fooling torpedoes.

If you read up on china's new hypersonic missile system you can get a feeling for why this shit is terrifying sometimes. Fractional Orbital Bombardment System is new and very scary for the USA missile defense systems. They effectively shrink the "we can see it range" down to a very small amount of time to respond. Combine that with MIRV warheads and decoys and it's a nightmare.

Ah, good point about the structural issue. But as for giving your position away, I meant it to be the last resort, when you're detected and under attack already.

> The other aspect is that these torpedoes can still be wired to the ship so you can continue to use the host sub's arguably better passive sonar systems and let the attacking torpedo get VERY close.

I don't know if there is any public data about how long the guidance wires are, but tens of kilometers seems like a pretty safe bet. Classic wire-guided TOW missiles have 3+ km of wire and are much smaller than a Mk-48 (about 6" diameter, vs 21")

>Fractional Orbital Bombardment System is new and very scary for the USA missile defense systems.

It's actually a fairly old technology as these things go, developed in the '60s and deprecated in the '80s. My understanding of HGWs that are currently being developed/fielded is that their potential FOBS aspect isn't what's scary--it's that they're more maneuverable than MARVs on traditional ballistic missiles and may be able to evade many currently fielded ABM systems.

That said, submarine warfare is indeed insane.

What’s an HGW?

Hypersonic glide weapon.

Yes several navies are working on torpedo interceptors.

https://www.defensenews.com/global/europe/2019/04/16/navies-...

Like chaff [0] or flares?

I wonder if you could triangulate the launch point though.

[0]: https://en.wikipedia.org/wiki/Chaff_(countermeasure)

From what I've seen on naval ships you'd launch it to the side that is incoming so you'd be behind the wall of Chaff. I think that would be significantly harder to triangulate because you'd mostly just see the noisy stuff up front and your original target would be behind the wall of chaff.

Chaff is also designed to reflect signals all over the place so that it's difficult to get accurate results back. This would make triangulating near impossible (if it's working as intended)

The problem is difficult due to the inability to use radar as a guidance mechanism for the "anti-torpedo torpedo."

Sure, but here I imagined you could just home on the attacker's active sonar.

Couldn't the hunter torpedo simply turn off its active sonar once the enemy was detected?

At that point, it already has enough information to get right up in the enemy's face.

But if the torpedo has pinged, the sub knows something's afoot, and it could quickly scan in that direction with its own active sonar (giving up your position be damned, we're under attack already) to guide its interceptors. Plus, the attack torpedo is now rushing ahead - and loud.

Sword and shield indeed; it seems the submarine tactics people must have a lot of fun playing with these scenarios.

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