Chinese Unmanned Underwater Vehicles (UUV)

mister unknown said:

How feasible is it to use these XLUUVs as undersea "loyal wingman" drones of sorts, kind of like how modern manned aircraft is increasingly using CCA UCAVs? Would they have the range & speed to keep up with manned SSNs & the rest of the PLAN CVBG? Or would they need some kind of "carrier" vessel to tow them along until they're needed for duty?

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How do the SSN communicate with the XLUUV underwater?

mister unknown said:

How feasible is it to use these XLUUVs as undersea "loyal wingman" drones of sorts, kind of like how modern manned aircraft is increasingly using CCA UCAVs? Would they have the range & speed to keep up with manned SSNs & the rest of the PLAN CVBG? Or would they need some kind of "carrier" vessel to tow them along until they're needed for duty?

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Underwater communication using the EM spectrum is quite a bit harder than when using the air as the medium. Bitrates are much lower, and emitting any kind of signal exposes you to a greater risk of detection. Acoustic signals could be used for short ranges, but you're again making yourself into a big target, and it would limit the range where you can operate as a cohesive pack. If it turns out that XLUUVs will be used to complement manned subs, they will probably have a greater degree of autonomy than CCAs by necessity and roam semi-independently.

Yes, autonomy underwater is the biggest issue. Its an issue even for USV, and there the basic technical challenges are far more trivial (the operational challenges in a contested environment are something else).

Torpedoes use wire (fibre optic) guidance for the same reason. In fact any breakthrough in underwater communications would probably have far more immediate repercussions for how torpedos and missiles can be used as opposed to controlling UUVs.

For the time being UUVs for reliable communication either need to rely on wire guidance like torpedoes or they have to deploy an emitter to the surface, and a crewed submarine would have to do the same. With obvious issues for detectability.

Basic question: how do UUVs currently communicate with manned assets?

i would imagine satellites is the best way for them to communicate. As long as they operate close to Chinese shores, they can probably surface or get close to surface enough where they can use some kind of floating communication equipment to TR with satellites. Of course, there is possibly also undersea network that allows them to communicate. Within 1IC, the options are quite abundant I would imagine.

So how feasible would it be for UUVs to communicate with manned SSNs in a collaborative combat environment? Granted direct, point-to-point communications would be faster if it were technically possible, but absent that, would this still be a fast enough, viable alternative?

mister unknown said:

Basic question: how do UUVs currently communicate with manned assets?

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They use acoustic communications near underwater modems or other vessels. They can use masts which involve piercing the surface which is a liability against radar. If possible SATCOM is preferred for its directionality.
For years there has been research on the use of blue lasers for communications with underwater assets but that is a megaclasssified topic.

tphuang said:

i would imagine satellites is the best way for them to communicate. As long as they operate close to Chinese shores, they can probably surface or get close to surface enough where they can use some kind of floating communication equipment to TR with satellites. Of course, there is possibly also undersea network that allows them to communicate. Within 1IC, the options are quite abundant I would imagine.

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I can see China daisy chaining small UAVs as underwater acoustic relays. There are interesting ultra-high-endurance propulsion systems that are being developed.
While looking at studies I saw a glider design that uses the temperature differences between different layers of the water as its energy source. It had a wax inside it that melts as the UUV rises to the surface. The material was one of those materials that contracts while melting. The contraction pulls water in which results in the glider starting to sink again. As it sinks the reverse happens. The wax freezes and expands, which pushes some water out. Of course any underwater glider is very slow but that isn't very important if it is just a relay and especially if it can be dropped from the air like some of the UUV they showcased.

China could be transitioning into mostly nuclear submarine fleet, with larger UUVs replacing the role of Diesel subs sitting at chock points in the event of a conflict.

UUVs for picket duty.

Attaching fiber optic cable from manned sub to unmanned sub drones is the best way to communicate. Think of it like an ethernet cable. Because in under water, signal is difficult to transfer wirelessly so to get real time data from the UUV, it has to attached to the manned sub

I assume the fiber cable is going to be very long.