Future Chinese "Supersonic" submarine

I could swear this has already been up here but for the life of me I can't find it.
 
TomS said:
sferrin said:
I could swear this has already been up here but for the life of me I can't find it.
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http://www.secretprojects.co.uk/forum/index.php/topic,1195.msg229572.html#msg229572
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Well Whaddaya know. The story I was following that led to it was dated today, and I didn't look close enough at the ultimate source to check its date. Sorry 'bout that. I guess this thread doesn't serve any purpose

While I'm not that worried, I wouldn't completely disregard it. After all, the US didn't believe the Soviets could rework titanium (after all we couldn't), build a submarine out of that material (and the way we finally proved that they could to ourselves is a story in itself) or a supercavitating rocket torpedo---until they did.
 
I've found what appears to be a basic diagram of the concept. Looking at the article you posted, they think they can get 70,000 newtons from a 2MW laser. I have no idea how well that compares to a standard propeller in terms of efficiency. I also have no idea how loud such a system would be, but given that it relies on "a detonation wave by plasma expansion" to drive the submarine forward, I can't imagine it would be silent. The article claims that because it has no moving parts it would be silent, but I seriously doubt that. Especially since a nuclear reactor would still be required to power this thing (granted, they can be very quiet these days).

The claims for the submarine being supersonic seem to come from the possibility of using the laser to generate cavitation bubbles around the submarine. I think I've seen that concept for supercavitation before, but the amount of energy they'd need to generate such a cavitation bubble seems very high (not to mention extremely loud).

This is before we consider whether this "supersonic" claim is in air or water. I'm assuming the former, since going supersonic in water seems ridiculous.

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If it happened you would need more than good navigation. Any little thing in the water would be a real headache and spoil the day big time.
 
Anything large that would rely on cavitation bubbles to move through the water at any kind of speed would be loud enough that enemy subs would hear it on the other side of the ocean.
 
MihoshiK said:
Anything large that would rely on cavitation bubbles to move through the water at any kind of speed would be loud enough that enemy subs would hear it on the other side of the ocean.
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One of the failings of both the Russian Alfa and Papa class high speed submarines, was that although streamlined, moving through water that fast creates noise- a LOT of noise. The article mentions they would be quiet-No, the propulsion system would be quiet, the submarine moving through water would not. And a "detonation wave" would hardly be silent. And the drag on the hull increases with speed; which is why the Papa required 80,000 SHP to hit 44 knots. Supercavitation helps, but if the last propulsion is at the aft end, how does this envelope the entire submarine. Also, as mentioned above when they say "supersonic", is that in air or water, because sound moves through water much faster than through air.

This resembles the fanciful articles published in Mechanics Illustrated.
 
Prophet141 said:
I've found what appears to be a basic diagram of the concept. Looking at the article you posted, they think they can get 70,000 newtons from a 2MW laser. I have no idea how well that compares to a standard propeller in terms of efficiency. I also have no idea how loud such a system would be, but given that it relies on "a detonation wave by plasma expansion" to drive the submarine forward, I can't imagine it would be silent. The article claims that because it has no moving parts it would be silent, but I seriously doubt that. Especially since a nuclear reactor would still be required to power this thing (granted, they can be very quiet these days).

The claims for the submarine being supersonic seem to come from the possibility of using the laser to generate cavitation bubbles around the submarine. I think I've seen that concept for supercavitation before, but the amount of energy they'd need to generate such a cavitation bubble seems very high (not to mention extremely loud).

This is before we consider whether this "supersonic" claim is in air or water. I'm assuming the former, since going supersonic in water seems ridiculous.

View attachment 727309
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Now imagine this but Godzilla sized. :D
 
Prophet141 said:
I've found what appears to be a basic diagram of the concept. Looking at the article you posted, they think they can get 70,000 newtons from a 2MW laser. I have no idea how well that compares to a standard propeller in terms of efficiency. I also have no idea how loud such a system would be, but given that it relies on "a detonation wave by plasma expansion" to drive the submarine forward, I can't imagine it would be silent. The article claims that because it has no moving parts it would be silent, but I seriously doubt that. Especially since a nuclear reactor would still be required to power this thing (granted, they can be very quiet these days).
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That is 6 or 7 orders of magnitude improvement over a deep space photon drive. The classic 'photon drive' takes 300MW per 1 Newton of thrust...
 
Scott Kenny said:
That is 6 or 7 orders of magnitude improvement over a deep space photon drive. The classic 'photon drive' takes 300MW per 1 Newton of thrust...
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In fairness, the method of operation is completely different. In a photon drive you're relying on the momentum of light as a stand in for the momentum of a working mass or fuel. In this instance, the laser is being used to heat the water into plasma, the shockwave from which will then push against and propel the submarine.

No doubt sending every whale on or under the Seven Seas onto their nearest beaches to escape the noise...
 
Prophet141 said:
In fairness, the method of operation is completely different. In a photon drive you're relying on the momentum of light as a stand in for the momentum of a working mass or fuel. In this instance, the laser is being used to heat the water into plasma, the shockwave from which will then push against and propel the submarine.

No doubt sending every whale on or under the Seven Seas onto their nearest beaches to escape the noise...
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And the continuous generation of shock waves would be readily detectable by acoustics. If it's a sufficient shockwave to propel a multi -1000 ton object at high speed, it would make one huge shockwave footprint.
 

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