Hacker News Reader

Comment by wahern | Hacker News Reader

Here's what CIWS look like: https://en.wikipedia.org/wiki/Close-in_weapon_system

Do those things have the capability to attack such tiny targets that are already close in? We're talking about something the size and speed of a bird. By the time you realize it's not a bird it's probably already on top of you. Moreover, they're small enough that they wouldn't represent a substantial threat to a ship in and of themselves (as compared to, say, an explosive-laden dinghy), and so perhaps not necessarily the kind of target that would've been specified for these weapons systems. I would imagine defenses for such small UAVs would be more in the vein of electronic countermeasures.

View on HN

> Do those things have the capability to attack such tiny targets that are already close in?

Yes

> We're talking about something the size and speed of a bird

Birds have nothing on stealthy, supersonic anti-ship missiles.

> By the time you realize it's not a bird it's probably already on top of you

In a war scenario all wildlife gets shot first. Modern systems developed in the past ten years also commonly have the capability to discern bird wings from propellers for this scenario. Hurray cheaper compute, everybody can run a SVM classifier in real-time now. Without spending too much money on your radar (40k USD? parts only) you can classify birds at about 0.5-1km away, who knows the exact capability of people with money to spend on the problem.

> I would imagine defenses for such small UAVs would be more in the vein of electronic countermeasures.

?Porque no los dos?

I don't think they can afford to see every bird as a threat during a battle. That means they'll also see every piece of shrapnel as a threat. And every piece of outgoing large munitions. I got the impression that speed and direction of travel are common filters. So something that's slow, tiny, and changing direction a lot is legitimately going to be hard to distinguish from a lot of non-threatening things.

I can't speculate on what's actually on US Navy warships right now, but I'm telling you commercially you can distinguish birds from drones under a kilometer away today. The knowledge has been around on how to do so with radar since 2006 https://ieeexplore.ieee.org/document/1603402, but even without that, there are numerous combined radar-camera surveillance systems out there for accurate target classification. Not like you don't have time to cue a camera to look at an interesting radar target when it's travelling slowly like a UAV might.

The military’s been able to distinguish this since the early 90s — at least. And yes modern drones didn’t exist in the 90s but other similarly-sized machines did, eg balloon-mounted telemetry devices.

Citation: personal experience with those sensor systems.

The parent is correct. They have considerable capacity to accurately classify everything in their regional vicinity in milliseconds. This is old capability.

Tracking millions of entities in your general space in real-time is definitely possible today. I have little reason to believe the US Navy cannot do it too.

Unless wildlife is wearing armor, the radar and even polarimetric light signature is vastly different between a bird and shrapnel even if it's not moving at all. Not all detection methods are heuristic.

An eg Exocet missile is only 12" in diameter when it's approaching you head-on. So optically it would be similar to a DJI-size drone. Thermal will be vastly different ;)

So I thought about it, and even if a small drone was loaded with explosives it really couldn’t damage a war ship. Unless it attacked the sensors.

A shaped charge hitting the EOSS, the radar dome, or parts of the Aegis system’s sensor array could potentially cripple the ship’s ability to defend itself.

No not by itself. Honestly I know very little about modern explosives but I could imagine a swarm of drones, made of or carrying explosives could converge on a critical section of a target additively making a substantial explosive force.

I know just enough about material science to say probably not. A munition needs to break or penetrate a surface to be effective. To do that it needs to apply a great deal of force in a short period of time- spreading the force out over space or time reduce the destructive capability of the munition. So getting hit 500 times by 1 lbs bombs is not the same as getting hit once by a 500 lbs bomb- it’s not additive, the 500 lbs destroys things the 500 1 lbs can’t.

That being said, I’d imagine being on the receiving end of 500 1 lbs explosives is still a very bad day.

Right, if I apply 1 pound of force to your head 520 times, you’ll be really annoyed with me. If I apply 520 pounds of force to your head once, I’ve just crushed your skull.

If each of those 1 lb bombs lands precisely on one of the ship's sensors, then that ship is out of action, even if its hull has not been breached anywhere.

One could imagine other payloads like chaff, smoke, or even paint or flash bangs to disable equipment and injure the crew perhaps. Not sure how efficient that would be though.

100 drones for misting gasoline, 10 drones for igniting it?

US uses Phalanx CIWS. Here is a video all about Phalanx https://www.youtube.com/watch?v=dKrpEfNaQO8&ab_channel=USMil...

From what I read, those quadcopters were far bigger than a bird, and even more noisier than civilian quadcopters, heard from hundreds of meters away.

Did I miss some description of the size of the UAVs?

Fair point. Based on the admittedly thin circumstantial evidence in the article, I assumed relatively small craft. For example,

1) Why would a Carnival cruise ship feel the need to disclaim involvement for anything except a small, COTS drone? (IOW, presumably they at least believed they could have been such small drones.)

2) 4+ were spotted together. Wouldn't those be audible, especially if much larger than COTS drones?

3) The lights ("white light", "red flashing light") suggests COTS drones, especially because the cruise ship also noticed them. If they were special purpose military or intelligence drones, why keep the lights on?

Granted, the supposed distances involved suggest otherwise, but the article never establishes why they believed the drones were necessarily flown such distances. Rather, it seems those distances are based on the presumption that the drones were flown from one of the ships with active AIS. But that's a rather dubious assumption in the context of someone buzzing military ships w/ multiple drones.

The Navy knows every ship that is anywhere close to it, whether or not it has its AIS turned on, even if it's underwater.

The Navy can know, if it wants. Cataloging every pleasure boat and fish trawler days or weeks after the fact is something else entirely.

Also, the Navy's recent history of situational awareness isn't the greatest. See, e.g., https://features.propublica.org/navy-accidents/us-navy-crash...

If you can detect it, it is dead.

https://youtu.be/bdwjcayPuag

For a UAV hovering over the helicopter pad I would imagine that small arms would suffice.

Shotguns. Automatic shotguns would seem to be right for this.

Most target shooters couldn't hit a drone that wasn't hovering let alone a sailor who had guns training several years back. A shotgun would be the way to get these guys when they got in close enough.

Reply on news.ycombinator.com