Supercavitation Submarine, possible? Options

[maeel]

The Main idea: a submarine of the size between a hunter/killer sub and a boomer but of the shape of a very aerodynamic spaceship.

It would have cavitators placed all over the hull to ensure a (allmost) complete cavitation bubble around the ship.

The ship would be powered by an aneutronic boron fusion reactor.
Propulsion would be offered by an magnetohydrodynamic drive system for shallow/tight waters and some sort of underwater jetengine, which would directly vaporize seawater with reactor plasma and provide the required thrust for supercavitation speed.

What do you guys think?

[TheUrbanMonkey]

cavitation is noise caused by the propellers creating air bubbles as they move through the water (IIRC), so why would you want a lot of that?

[bibliophile20]

Because cavitation is a bubble of air; air has less resistance and less drag than water which is why you can move much faster in air than in water; having a "super-cavitating" bubble around a submarine would thus allow you to achieve incredible speeds in the water (VA-111 Shkval supercavitating torpedoes have been clocked at speeds in excess of 200 knots (~370 km/h))

Wikipedia on supercavitation

[toturi]

In effect, warp speed underwater.

[pbangarth]

How would the crew of such a ship detect other ships or torpedoes through the noise generated by their own ship?

[maeel]

they would not, but they could move to the battlefield much faster where they would switch to MHD, which would make them very silent.

[Garrowolf]

There is a nice scifi web setting based on this called Deep Angel. It might give you some ideas.

[Fix-it]

[Garrowolf]

A towed array wouldn't work at those speeds. You would drown it in noise.

I think that you would almost be forces to use active sonar or indirect sensors from other craft or satellites.

[maeel]

thanks garro, i looked into it, pretty nice stuff.....

[Garrowolf]

I love the graphics on that site

[PBTHHHHT]

Yikes, all cool is moving fast, but for subs being detected means death. That the enemy knows where you are and also where you stop when you get to the battlefield...

I can see it more for an escape situation, but even then only for extreme situations. Can the sub supercavitate far enough to get out of enemy aircraft who can drop torpedoes on their location? That's also something to consider if used as an escape.

[SpasticTeapot]

IMO, slow and steady wins the race.

There's also something to be said for drones. Explosive drones.

[Garrowolf]

Well part of the point of a supercav Sub is that it can go anywhere in the world much more quickly then a regular sub. They are still hard to detect. They are moving too fast for a torpedo to hit (unless it is a supercav torpedo). They get into the area that they are needed and then go quiet and hunt. They don't hunt at high speed.

[Catharz Godfoot]

If you're using fictional tech anyway, just say the hull is hooked up to act as a giant noise-canceling speaker array, and you have a set of 3 'hulls' projecting into the water and holding sensor suites.

[Vertaxis666]

There are several reasons why this won't work.

1. Supercavitation is noisy. Submarines are the ultimate stealth weapon and depend on their silence for survivability and advantage. A supercavitating sub would be heard underwater from several hundred nautical miles away.

2. Propulsion requiring the intake of water would fail since the submarine resides withing a supercritical bubble. There is no contact with the water.

3. To maintain supercavitation, you would sacrifice all manoeuvrability. The sub would be travelling in a straight line at all times with a manoeuvering capability of +/- 1-5 degrees only.

4. The sub would be blind travelling at supercavition speeds. No only would the noise flood the sonar, but any sensor probe push outside the supercritical layer would rapidly erode and fail. This leaves only inertial guidance for position, and no sensors to detect targets or obstacles.

As a weapon, the shkval is deadly. But scaling up to a sub just doesn't make any sense.

[maeel]

Actually it was not intended for military purposes but as a freighter. Sure superfreighter can move much more stuff, but they are not as fast. Planes are faster but cant move as much.

As for the waterintake and the sensors: the cavitators do have contact with the water. Electronic systems can filter out the own noise for sonar purposes.

however the stuff i read at deep angel, made me to rethink the design, now the sub is powered by an oxygen hydrogen rocket engine.

[Garrowolf]

A supercav sub would be using rockets to move that fast. We know about super cav because of missile fired underwater have this as a side effect. I think that the Russians even have a supercav torpedo.

While it was operating in Supercav mode it would operate more like a plane in dense fog. It would also be moving very fast. It could move into an area and then go silent. I'm sure they would develop tactics to deal with the initial noise like coming in on the other side of an island. Then they would go silent. This would at least make it hard to figure out where it was and it could hide in it's own arrival noise for a while. An opposing naval that was nearby enough to do anything about it would have a large contact that they couldn't find immediately afterwards.

Also you can use this to get into allied waters and then launch a short range missile salvo into a different land locked country. That country wouldn't have a navy to do anything about it and you have just responded faster then anyone knew you could.

[maeel]

In military terms i wouldnt see supercavitation subs as competition to normal subs but to surface warships.

btw garro: duck...duck...duck... GOOSE!

[Fix-it]

[KarmaInferno]

There's too many problems associated with supercavitation for it to be used as a main propulsion system on any sort of craft.

You've taken the number one advantage submarines have and tossed it out the window. Stealth. Even if you turn it off when you get to your hunting ground, the enemy can easily extrapolate a radius where you're likely to be at.

Whereas a normal sub can slip into an area with the enemy not even knowing it's there until it is far too late.

You can only go in straight lines, and you're blind while it's on. That alone makes it massively unsuitable.

It works for torpedoes because by the time you are launching those, stealth is no longer as much of an issue. The enemy will know something is up no matter what kind of torpedo you use. Torpedoes of this sort don't have to worry about being blind or moving in straight lines - targeting is handled by the sub, not the torpedo. The idea is to have the torp move too fast for the enemy to evade.

Heck, if you're worried about the torpedo track giving away your sub's position, you could probably design one so it takes an indirect path to the target, only turning on the supercavitation when it's coming in from a different direction to the enemy than where the launching sub is at.


-karma

[Garrowolf]

The supercav mode is for getting into that part of the world - not for hunting. The problem with subs today is that they are fairly slow. It takes a long time to get one close. That is why we have so many of them.

Maeel Duck? What?!?

[Lagomorph]

Just drop the subs from space platforms, they'll get where they are going pretty quick that way. And as a bonus they are undetectible by sonar that way until it's too late. The best of both worlds :)

[hyzmarca]

Two words, amphibious aircraft. Take cargo jet and have an Ally Spirit of Water in the form is a whale inhabit it, going for a Hybrid Merge.

[Kyoto Kid]