Chinese Unmanned Underwater Vehicles (UUV)

BoraTas · May 9, 2024

broadsword said:
Is 140dB a mistake? It is louder than a military jet aircraft taking off from an aircraft carrier deck.

Underwater decibel is different from normal decibel. Underwater decibel is basically normal decibel + 62.
And really, what they mean by "<140 dB". The speed and the context would be important here. Is that a discrete component or broadband noise? 140 dB is, nevertheless, a lot. If it is the strongest discrete component in slow speeds, it equals WW2-era SSKs. If it is broadband noise at 12 knots, then the thing equals the Kilo (877) class. Such a wild gap...

siegecrossbow · May 9, 2024

Maikeru said:
Covert Shores article on newly seen UUV. He says China is leading in this new technology.

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Maybe this is what sank in the Yellow Sea last year instead of the Type 093.

by78 · Jul 4, 2024

A paper on fault-tolerant X-rudders for UUVs.

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Abstract: The X-rudder concept has been applied to more and more autonomous underwater vehicles (AUVs) in recent years, since it shows better maneuverability and robustness against rudder failure compared to the traditional cruciform rudder. Aiming at the fault-tolerant control of the X-rudder AUV (hereinafter abbreviated as xAUV), a fault-tolerant steering prototype system which can realize dynamics control, autonomous rudder fault detection and fault-tolerant control is presented in this paper. The steering prototype system is deployed on a verification platform, an xAUV, in which the monitor software is developed based on the factory method and the onboard software is developed based on the finite state machine (FSM). Dual-loop increment feedback control (DIFC) is first introduced to obtain smooth virtual rudder commands considering actuator’s limitations. Then the virtual rudder commands are transformed into X-rudder commands based on the mapping theory. In rudder fault diagnosis, an optimized particle filter is proposed for estimating rudder effect deduction, with proposal distribution derived from unscented Kalman filter (UKF). Then the fault type can be determined by analyzing indicators related to the deduction. Fault-tolerant control is addressed by dealing with nonlinear programming (NLP) problem, where minimization of allocation errors and control efforts are set as the optimization objectives, and rudder failure, saturation and actuators limitations are considered as constraints. The fixed-point iteration method is utilized to solve this optimization problem. Many field tests have been conducted in towing tank. The experimental results demonstrate that the proposed steering prototype system is able to detect rudder faults and is robust against rudder failure.

tphuang · Aug 6, 2024

https://twitter.com/i/web/status/1820642808799367174

now we have robotic shark in the seas.

It's unclear to me what advantage such a UUV has over your traditional sharks. Maybe it's just harder for other side to spot it.

lcloo · Aug 6, 2024

Whale sharks are the largest fish species in the world. Their confirmed longest length is 18.8m, using this size is ideal for long endurance and large payload.

Whale sharks are slow swimmers, which means fish shape UUV can easily mimic a whale shark's movement than that of fast swimming great white shark or large tuna fish.

by78 · Oct 16, 2024

An interesting

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from the 702 Institute that hints at a very large unmanned underwater vehicle.

tphuang · Oct 30, 2024

I was doing some thought experiments today with @BoraTas

Big question in my mind, how good and how much range and capabilities can we expect out of a XLUUV?

things to consider that since you don't have humans in the submersible, you can devote greater % of space to batteries. You don't have to ever ventilate since there is nobody in there, so that makes it inherently stealthier than 039C.
You don't have to raft that much since there is nobody in there making noise. eMotor and eDriveTrain should be fairly quiet. The only other thing that could make noise are the sonar and computation power in there.

and of course, you need some way of communicating underwater and or with satellites, but I think PLAN is pretty good with that already and getting better.

So, the math

3000 ton SSK uses 30-40kW for propulsion at 4 knots.
Let's say we have a 300-t single hull XLUUV and uses 1/3 of mass for battery & maybe 1/3 for eDrive/Motor/computation & remaining for sonar & everything else like torpedo tube (idk). Maybe it can use just 20kW for movement & power the systems.

100t * 0.2 MWh/t = 20 MWh battery pack. I use 200kWh/ton here because while the battery pack itself would have higher density, the protective layers and such would lower energy density to around 200kWh/ton. Of course if they use SSB, I could see battery pack here being twice the density level.

so 20 MWh with upward limit of 30 to 40 MWh.

Using 20kW for energy consumption. That would be anywhere from 1000 hours to 2000 hours in endurance. 1000 hours at 4 knots would be 4000 nm. 2000 hours at 4 knots would be 8000 nm.

For latter, they'd be able to go to Hawaii, launch torpedoes and then come back. Or they could just stay within 2IC, don't move and patrol there. For example, increase sensors density from Taiwan to Guam or all the way to SCS and East side of Philippines or to the East of Japan.

LuzinskiJ · Oct 30, 2024

tphuang said:
I was doing some thought experiments today with @BoraTas

Big question in my mind, how good and how much range and capabilities can we expect out of a XLUUV?

things to consider that since you don't have humans in the submersible, you can devote greater % of space to batteries. You don't have to ever ventilate since there is nobody in there, so that makes it inherently stealthier than 039C.
You don't have to raft that much since there is nobody in there making noise. eMotor and eDriveTrain should be fairly quiet. The only other thing that could make noise are the sonar and computation power in there.

and of course, you need some way of communicating underwater and or with satellites, but I think PLAN is pretty good with that already and getting better.

So, the math

100t * 0.2 MWh/t = 20 MWh battery pack. I use 200kWh/ton here because while the battery pack itself would have higher density, the protective layers and such would lower energy density to around 200kWh/ton. Of course if they use SSB, I could see battery pack here being twice the density level.

so 20 MWh with upward limit of 30 to 40 MWh.

Using 20kW for energy consumption. That would be anywhere from 1000 hours to 2000 hours in endurance. 1000 hours at 4 knots would be 4000 nm. 2000 hours at 4 knots would be 8000 nm.

For latter, they'd be able to go to Hawaii, launch torpedoes and then come back. Or they could just stay within 2IC, don't move and patrol there. For example, increase sensors density from Taiwan to Guam or all the way to SCS and East side of Philippines or to the East of Japan.

If the batteries are rechargeable, install a power source to do that, then that XLUUV can become a loitering munition platform itself that has unlimited range. Then why stop at Hawaii? If you can go past Hawaii, then why stop at torpedos?

tphuang · Oct 30, 2024

LuzinskiJ said:
If the batteries are rechargeable, install a power source to do that, then that XLUUV can become a loitering munition platform itself that has unlimited range. Then why stop at Hawaii? If you can go past Hawaii, then why stop at torpedos?

So if you want to make it go further then putting a stirling engine in there would make the most sense. But that would add cost & complexity.

making a battery electric only uuv for China is super easy and cheap.