China developing supersonic submarine powered by a rocket motor.

[NASAFanboy]

Or else what? The Chinese will develop a capability the Soviets had decades ago? Supercavitating torpedoes are a bit unusual, but not new.

Shhh, they don't know. Congress aren't engineers, and "suoercavitating" sounds hi-tech even if it isn't. This would cause a massive boon for science in the USA if used correctly. Remember, the government and population aren't scientists and engineers. Slap on a fancy and intimidating name to another countries weapons project and they'll demand a counter project to be set up.

[WestAir]

Sounds like a supersonic blimp would be easier to operate.

[K^2]

And way more fun.

[Seret]

I don't think the suggestion made in the article that this is applicable to submarines should be taken very seriously. This is clearly technology for weapons or maybe ROVs.

[magnemoe]

Why can't they use systems similar to RCS for steering?

The russian torpedo uses fins who touch the edge of the bobble, knowing where to go is more a problem sonar neither passive or active don't work.

Not sure how the torpedo solved this, perhaps it was controlled by the sub all the way.

Note that the Russian torpedo was mainly a weapon to scare other subs, Some sub launches a long range torpedo against you, you launch a high speed cavitating torpedo back.

This force the enemy too try to avoid it and this will break the control wire to their torpedo.

It was also a research project obiously, they hoped to be able to make more controllable torpedoes in the future, one idea might be one who travel normally then start cavitating the last bit, they was afraid the US would develop torpedoes to intercept other torpedoes.

[jfull]

It definitely wouldn't be feasible for anything manned, and wouldn't have much range, but it could be used for both torpedos or an unmanned sub equipped with its own torpedoes or missiles.

[Seret]

Not sure how the torpedo solved this, perhaps it was controlled by the sub all the way.

IIRC they were basically just stabilised, not guided. At those kind of speeds you can be reasonably sure your target isn't going to dodge, especially since they originally carried a nuclear warhead. The Soviets knew that the NATO boats were highly likely to be able to shoot first as they were so much quieter, they wanted a weapon that could return fire and hopefully sink the NATO sub before it's (wire-guided) torpedo could reach the Soviet boat. The idea was just to turn towards the point the torpedo was detected and fire a Shkval. If normal torpedoes are Sidewinders this thing is a Zuni.

[sgt_flyer]

The russian's nuclear tipped torpedoes were only meant for destroying US biggest aircraft carriers (they didn't know how they would be able to sink one of those without using nukes ) (and with the shkval speed, dodge or countermeasures would be really difficult to do)

For achieving control on the shkval torpedoes, it seems they play with diferrent things : the fins skimming on the bubble surface (basically, creating assymetric drag, because the tip would be slowed down by water), moving the bubble generator on the nose to change the bubble's shape, and for most recent versions it's even thought they might use vectored thrust. (Apart from those, i don't know how they would be able to control a supercavitating vehicle)

Also, darpa announced they are working on supercavitating subs since 2005 (program Underwater express) seems they even started building quarter size prototypes for trials.

Edited August 26, 2014 by sgt_flyer

[Idobox]

While it could possible to build manned submarines this way, there is absolutely no reason to do so. The only reason submarines exist is because they are difficult to detect, because they are inferior to normal ships on every other aspect. If you want to move fast, a plane or a hovercraft make much more sense.

The main point of the article is that they could make very fast torpedoes than can steer, which would be a formidable weapon for attack submarines.

[lajoswinkler]

I get that cavitation can push water out of the way. What I'm saying is, the transverse cross-section of a submarine would be quite large, and the vehicle would have to push that area-times-the-speed volume of water out of the way, with sea water being many times more massive, viscous, and under far higher pressure than air at the same speed. What I'm meaning is, one can't get around the conservation laws, and no matter which means is used, a tremendous amount of energy is going to be needed to move that mass of water out of the sub's way.

But I don't think I'm expressing myself well, without the technical background and terminology to say what I mean.

Exactly. The bulkness of the material needed to be shoved around is too much. What works for a small missile doesn't have to work for a submarine.

[Seret]

So does anyone who understands the physics involved know how feasible it is to scale up?

[andrew123]

The speed of sound is 4828.032 km/hr underwater. Good luck trying to create an amphibious antimatter drive.

[Idobox]

Sounds like a supersonic blimp would be easier to operate.

http://en.wikipedia.org/wiki/Orbital_airship

Some people actually consider this seriously

[JDCollie]

Sounds like a supersonic blimp would be easier to operate.

No no no, it needs to be a supercavitating blimp. Supersonic is so last century.

[Camacha]

propellers can have cavitation around their blades

It is actually one of the bigger problems with propellers. The imploding bubbles that appear in areas of low pressure do that with such violence that a propeller can be damaged quickly and thoroughly. When this phenomena is not properly controlled, structures can fail fast and catastrophically.

[Jesrad]

Some people even try to use the power of those bubbles to trigger fusion reactions. That's how powerful and dangerous they are.

[Nao]

Some people even try to use the power of those bubbles to trigger fusion reactions. That's how powerful and dangerous they are.

This is something that a "pistol shrimp" can do! . Maybe that's the secret? Maybe Chinese, have already weaponized their shrimps and are just looking for a fast delivery sub since the shrimp's destructive range is too small?

Also a wiki link:http://en.wikipedia.org/wiki/Sonoluminescence on the fusion in bobbles and shrimps.

[Herr Doktor Strangemember]

Exactly. The bulkness of the material needed to be shoved around is too much. What works for a small missile doesn't have to work for a submarine.

Well Electric Boat is building a 100ft sub with that tech to deliver payload or small units of troops to shore in littoral operations, now the top speed is around 100kts but that is game changer in terms of speed for those kind of ops.

I get that cavitation can push water out of the way. What I'm saying is, the transverse cross-section of a submarine would be quite large, and the vehicle would have to push that area-times-the-speed volume of water out of the way, with sea water being many times more massive, viscous, and under far higher pressure than air at the same speed. What I'm meaning is, one can't get around the conservation laws, and no matter which means is used, a tremendous amount of energy is going to be needed to move that mass of water out of the sub's way.

But I don't think I'm expressing myself well, without the technical background and terminology to say what I mean.

So does anyone who understands the physics involved know how feasible it is to scale up?

Understand...kinda. The torpedo/ship would look like an early sci-fi rocket that was mating with sword. Think a stubby dart or a stretched bullet, kinda. At the point of the 'dart' due to it's small cross section you create the bubble, using whatever, a combination of gas forming the bubbles at the tip, and the rocket engine at the back. As the the supercavitating torpedo/sub accelerates the speed of object forces the body into the bubbles at the nose lowering the drag caused by the water, allowing the speed to increase still again. At a certain point the 'tip' of the supercavitating object is doing most of the work in forming the bubble, creating an area of low pressure that is below the vaporization point of the water. As the speed increases the whole object is now in the bubble that is formed by the object. The bubble depends on water pressure, deeper harder to form, shallower easier.

Could you really 'fly' underwater at supersonic speeds...I really doubt it and anyone tries let me know in advance because the YouTube vid will be glorious in a high energy way.

IIRC the Russian torp was designed as an anti-torpedo torpedo with a small nuclear warhead, the upgraded version with a conventional warhead and better guidance was then used as a anti-sub weapon might still be able to shoot torps, that I don't know.

Again this all from stuff I've read over the years so I might be wrong, wrong-ish, or have my head up my @$$.

Regards.

[Stargate525]

Surely one of the big benefits of a submarine is the stealth factor. I can't really imagine the military application of a submarine, no matter how fast, that leaves a giant trail of frothing water after it.

[Sky_walker]

Surely one of the big benefits of a submarine is the stealth factor. I can't really imagine the military application of a submarine, no matter how fast, that leaves a giant trail of frothing water after it.

Maybe they try to scare the s*** out of Americans? You know... it's like on these self-defense courses where the first advise they give to the girls is "shout as loud as you can". lol

And besides - let's face it: conventional torpedoes would be useless in any attempt to catch something like that.

So in a pure theory - it could approach target silently and when fired upon - just "engage warp drive" and get the hell out.

[Kryten]

It'd certainly be impressive as a technological achievement, if nothing else. I'd love to see the face of the average congressman when informed the Chinese have a sub ten times faster than anything in the USN.

[Skyler4856]

It'd certainly be impressive as a technological achievement, if nothing else. I'd love to see the face of the average congressman when informed the Chinese have a sub ten times faster than anything in the USN.

So basically, the Chinese plan would be to start an arms race with the US, and have the instigator be a technology that doesn't really work?

[Sky_walker]

So basically, the Chinese plan would be to start an arms race with the US, and have the instigator be a technology that doesn't really work?

To start a real arms race with US they'd need much more than "just" supersonic submarine - even if it'd work flawlessly.

Though on the other hand - the arms race have already begun, though it doesn't involve US as much as it does other countries in proximity (eg. India).

[gooddog15]

To start a real arms race with US they'd need much more than "just" supersonic submarine - even if it'd work flawlessly.

Though on the other hand - the arms race have already begun, though it doesn't involve US as much as it does other countries in proximity (eg. India).

well, they are starting to test Hypersonic missiles as part of a delivery system for nuclear weapons, which they are planning to use as a deterrence against the U.S.'s ICBM's and Anti ICBM systems. the U.S. is also doing the same thing.

[Seret]

Surely one of the big benefits of a submarine is the stealth factor. I can't really imagine the military application of a submarine, no matter how fast, that leaves a giant trail of frothing water after it.

Exactly. The nuclear missile boats have one job: stay quiet. Even for an attack boat speed is far less important than stealth. They often creep around at far less than their top speed in order to be quieter. Even for special forces missions I can't really see a lot of use for a small high-speed sub that you could hear coming from half way across the world. Maybe I'm just being unimaginative?

For weapons this technology is ideal, since firing any kind of torpedo means making a lot of noise anyway.