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Super Cavitation and the Truth

by christian on November 17, 2009

super-cavitation

Yesterday we received a call on our new Tip Line wondering if the Russians and US were working on submarine technologies that create an air bubble in front of the sub that allows it to travel 3x the normal speed.

Here’s what our readers asked:

This is more of a “Is it true” tip?? Someone told me just last night that the Russian Navy & the US Navy are separatley working on “an air bubble in front of a ship (sub) can make it travel 3 times its normal speed & that it was already tested on a torpedo & it moved as fast as 300 mph under water. Is there any truth to this story?? I am not beleiving anyone or any story unless I see it posted here or on military​.com. Can you let me what if anything you’ve heard about this. Thanks…

I don’t know much about subs, but I do know guys that do. So I sent this query on to our friend Joe Buff who had this reply (be sure to read his earlier post on DT regarding this subject):

Sounds like supercavitation. USSR/Russia has had supercavitating rocket torpedoes since the Cold War. USN also developed a good one prototype but decided not to deploy, preferring the mark 48 ADCAP torpedo. USN right now doing good work w. GDEB on “Underwater Express”, a 100-knot manned minisub which would give a “really quick and sonar-deafening getaway vehicle” for SEALs near the beach/surf zone.

The process uses rocket propulsion to get the underwater hull/vehicle going fast enough to create a partial-vacuum bubble around itself, eliminating water flow resistance against hull (but not the need to push water around and away from the bow/tip). Rocket engine burning fuel provides thrust allowing very high speed (200 to 300 knots for a sharp-tipped torpedo) not possible using a traditional rotating water screw (as in Ohio class) or pump-jet turbine (as in Virginia class).

I’ve not heard of this being applied to surface ships, where I think it would not work, and where air cushion, hydroplaning, or wing-in-ground-effect would give high speed much more practically. There are separately though things like “Prairie Masker” which emit bubbles (engine exhaust I think, not “air”) to isolate hull noises from the sea to provide acoustic stealth for the ship against enemy subs & sonars.

Well, there you have it. Hope this answers the mail and please keep the tips coming…

– Christian (with Joe Buff)

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{ 33 comments… read them below or add one }

A. Physicist November 17, 2009 at 2:12 pm

Supercavitation is an interesting idea. I don't think it's likely to be practical for anything larger than a torpedo, at least not from what I've seen. Boundary layer separation is easy-ish to control for a relatively small, radially symmetric object, compared to a hulking steel hull. There's just no way to reduce wave drag on these big ships via separation control.

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pedestrian November 17, 2009 at 2:15 pm

While supercavitation provides high speed underwater, the underwater vehicles will suffer from noise that will be vulnerable to enemy sonar, and suffer from noise that will result in noise blinding its own sonars. This is why Shkval is a dumb rocket that could not be guided and not a majority in modern day torpedoes. I would expect underwater rocket is not ideal for long range with the combination of this. There is a need of counterpart of ramjet/scram jet, or a turbo jet at the least to combine with supercavitation for diving long distance.

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Ed! November 17, 2009 at 3:34 pm

The Shkval torpedo was designed for a couple purposes in mind. It can be used as a final shot in the dark in the event the Russian sub is about to be hit and wants to shoot back at the attacking vessel and not care of a targeting solution. It can also be used against larger surface vessels if the vessel using the torpedo can get close enough. The target won't be able to maneuver out of the way if its a side on shot or even a shot at the aft of the ship.

It is loud and it is very streamlined. Using this for a large vessel such as a submarine does mean it loses any stealth it has. It also loses the ability to detect anyone else. Both were mentioned above. The other is you would have to remove all items that would take away from the bubble, meaning the sub would have to look like a missile to begin with. We have also not tested the effects of such speed on humans underwater and at such pressures.

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chrisram November 17, 2009 at 5:10 pm

Interesting technology (thanks Christian for coming back to what brings me to this site, TECH) but not sure it could be applied to surface ships (I think that was mentioned).

Supercavitation might be a great escape technology to allow a submarine to escape a hostile area if detected or if a torpedo is incoming. Unfortunately it makes you blind and deaf so it would seem to be a last ditch effort. It could perhaps also be applied to torpedoes for the terminal phase of target prosecution. In other words it tracks it's target and once it has a clear solution on the target it kicks in the supercavitation and reduces the hill chain time dramatically and eliminates the possibility of countermeasures deployment, manuvering, etc.

Very interesting technology….

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joebuff November 17, 2009 at 6:11 pm

The Soviet supercavitating torpedoes were intended to have nuclear warheads, thus avoiding the need for much or any of an accurate firing solution. The Naval Underwater Weapons Center has reportedly developed a supercavitating torpedo that is able to use good target-homing technologies. (But again, Sub Force much prefers their Littoral Capable Mark 48 ADCAPs with immediately reconfigurable software download capability.) UNCLASS conjectures on how this could work include a throttle-able rocket allowing the weapon to slow enough to revert temporarily to conventional homing, or a rocket tip with an active sonar sensor "window" that projects ahead of the supercavitating bubble into otherwise undisturbed water for a decent sound path to/from target. Electric Boat reports that, through the details are top secret, they have solved the control and stability problems for a 100-knot command minisub with maybe 2 crew, 4 SEALs + equipment. It would usually be battery powered in the role of an ASDS-type vehicle, but it could in an emergency-egress scenario engage the supercavitation drive to "get the hell out of Dodge." Also BTW FYI, in one of his KEWL novels Michael DiMercurio depicts a future full-size SSN that has such an emergency escape/evasion drive. One problem is it melts the back half of the sub, but it does get his hero's submarine out of Dodge very nicely!

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ohwilleke November 17, 2009 at 6:23 pm

A torpedo like that, married to an otherwise unimpressive coastal diesel submarine could turn a mild threat into a deadly one.

I'll believe the mini-sub claims whe I see it. Given the dismal failure of the U.S. DOD to make an even remotely affordable mini-sub for SEAL transport that had no really exceptional features, I'm highly skeptical that Electric Boat can pull off an even more difficult, high tech version of the same concept.

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Curious November 17, 2009 at 6:52 pm

Wasn't Iran said to have bought up some Shkval torpedo's a while back?

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DavidB November 17, 2009 at 8:16 pm

Good comment joebuff, I was going to mention DiMercurio's novels but you beat me to it. Methinks this is one of those issues of "fact" following fiction…

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chrisram November 17, 2009 at 8:26 pm

The mini-sub (ASDV) program was a textboox case of several thing sthat plague the DoD acquisition process: no operational requirement, poorly defined requirements, immature technology (batteries), poorly performing contractor (NG) and trying to go it alone and not build on already successful platforms.

The Swedes already have a successful mini sub program (Sea Dagger) which was recommended to be used as the ASDV platform. This was rejected becasue the SEAL Teams wanted to be able to deliver more personnel and now they have a system that does not work, is louder than the sub that launches it (which makes sub guys really happy) and catches on fire.

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freefallingbomb November 18, 2009 at 5:32 pm

Part I :

To the poster "chrisram" :

You wrote: "…the S.E.A.L. teams wanted to be able to deliver more personnel and now they have a system that does not work, is louder than the sub that launches it (which makes sub guys really happy)…"

Everybody knows that U.S. American (or other) special forces don't flee all the way "home across the oceans" after an operation in midget submarines, rubber boats or riding on jet skis, like James Bond: There's BOUND to be some helicopter waiting behind the horizon, meaning in turn an aircraft carrier (the U.S. Armed Forces don't have long-range hydroplanes), or some larger submarine, or civilian cargo ships in disguise, etc. .
Even SEAL delivery vehicles (S.D.V.'s) with underwater rocket engines and supercavitation won't have great ranges either, which teaches even dumb enemies to go after the "mother"…

(Continued)

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freefallingbomb November 18, 2009 at 5:33 pm

Part II :

I also don't believe that S.D.V.'s will use super-cavitation to insert divers in the first place, even if speed was of absolute essence for the mission, because the underwater rocket engines would immediately denounce their approach, even to very distant sonars.

So, any future S.D.V. will probably combine TWO types of engines:

1) A super-silent water-jet engine for discrete insertions and extractions under normal circumstances

and

2) a rocket engine with supercavitation for extractions or abortions of missions if shit happens (at sea).

(Continued)

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freefallingbomb November 18, 2009 at 5:34 pm

Part III :

I also don't believe that a SEAL team would endanger a (their own!) submarines' crew of 100 – 200 seamen by using supercavitation all the way back to their submarine, thus giving its exact position away, and knowing that afterwards it can never produce the same speed too to escape from the enemy's anti-submarine forces: They'll probably drive deliberately some time in the wrong direction with supercavitation, just to escape persecution at the beach (a feint), then turn off that loud engine and use the second, noise-less engine to dive to in the right direction, to the waiting submarine.

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gsak November 20, 2009 at 1:16 am

chrisram is right. Especially about the "fire" part. :)

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Valcan November 17, 2009 at 8:38 pm

Remind me again why they need a superfast mini sub?

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stephen russell November 18, 2009 at 1:30 am

2 bad it cant work for manned sub IE dual power:
Nuclear Jet screw & Supercaviation rocket mode in a super advanced VA class sub type.
Darn fuel for the rockets though.
Darn.

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Byron Skinner November 17, 2009 at 10:40 pm

Good Evening Folks,

First off to Ward, put ID’s back up.

Supercavitation is the stuff of science fiction. It’s not out of the realm of possibilities by why? Besides the huge expense of development. it would be nosey at underwater speeds of 100 Knts. the sub wouldn’t be able to use passive sonar listening and would seem to be making itself a target for ASW forces.

I agree with whom ever made the comments regarding the Mk. 48, and torpedos in general, they are legacy weapons. The role of the SSN is more then just sinking surface ships and other subs. There are other and more efficient weapon systems already on an SSN to deal with other vessels above or below the surface then the torpedo. It now appears that the Virginia Class will be done with 30 boats and the last block of Virginias very well might not look like the SSN Virginia. The next SSN will be quite different the current Virginia’s.

Look for an increase in the number of vertical launch tubes in numbers perhaps to as many as 96 and amidship instead of the current 12 in the bow section of the sub. The incorporation of a wet well that can launch and recover UUV’s while submerged. With the development of broadband communication to and from submerged vessels with will greatly increase the subs situational awareness and connection to the chain of command with out having to surface, come to periscope depth or send up a communications buoy, the missions of the SSN’s will include more ISR, EO Recon., ADM, mine/counter mine warfare and support of the ground mission as well as sea control and Spec. Ops. missions.

ALLONS,
Byron Skinner

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Ed! November 18, 2009 at 11:20 am

Yes Curious, Iran supposedly has them and showed them off during one of their exercises about 2 years ago, but nothing since.

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joebuff November 18, 2009 at 5:23 pm

I've been told that Seawolf's flank speed is comparable to that of the Alfas or maybe even a tad of a knot or a few faster, suggesting that the Alfas were just nuclear powered. Sources also tell me that any supercavitating propulsion system would be horribly noisy due to the acoustic signature of the rocket engine(s) required in all current technical approaches. Iran's "test-demo" of supercavitating torpedoes a couple or so years ago was described afterward in some American sources as having been faked, just like some (but not all) of their multiple ballistic missile launch tests have been faked. Also, supercavitation is not sci fi, it is totally real. It was (and is?) operational in the Russian (ex-Soviet) Navy. It has been tested successfully in a 1/4-scale prototype of the USN/GDEB "Underwater Express" manned minisub R&D project, which had reportedly achieved breakthroughs in the tech needed for stability and maneuverability at 100kts.

So far the only mission profile that yours truly can think of or that project officials have mentioned publicly is the one mentioned in some earlier comments above here: a rapid emergency egress away from the beach zone where the opposition does not have sea denial forces in any great depth.

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DavidB November 18, 2009 at 8:11 pm

All these comments about noise, have you even CONSIDERED the user of such technology may care not a whit how much noise they leave behind in the ocean? Seriously, how many coastal nations do you think ACTUALLY HAVE sonar monitoring of their coastline? If there's nobody there to listen, do you care how loud you are? If a tree falls in a forest and noone is there to hear it, does it still make a sound? I mean really guys, THINK about it!

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freefallingbomb November 18, 2009 at 4:34 pm

Could super-cavitation have been the true secret behind the 8 Soviet 1977'-vintage, experimental Alfa-class submarines' record speed and maneuverability, instead of alleged "unsafe nuclear engines" (Yankee bad-mouthing…) ? Super-cavitation doesn't NECESSARILY imply having a loud rocket engine on board!

If so, then all U.S. American submarines built afterwards, including the "ultra-modern" 2,8-BILLION-dollars-a-piece Seawolf-class submarines (1989 – 2005) were OBSOLETE before they were even built, launched and baptized!

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freefallingbomb November 18, 2009 at 11:01 pm

To the poster "DavidB" :

…………………………………………………………………………………………………………………………………………….

You wrote: "All these comments about noise, have you even CONSIDERED the user of such technology may care not a whit how much noise they leave behind in the ocean?"

You mean that once the SEALs are wet again, "nothing more" can happen to them? Or to the big submarine that picks them up?

…………………………………………………………………………………………………………………………………………….

You wrote: "Seriously, how many coastal nations do you think ACTUALLY HAVE sonar monitoring of their coastline?"

These?

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

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freefallingbomb November 19, 2009 at 2:46 am

I did NOT reduce my original link to a "bit-ly" ! That was "Defense Tech" who did that! My original link led to Wikipedia's list of navies.

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freefallingbomb November 18, 2009 at 11:54 pm

Part I :

To the poster "pedestrian", who wrote:
"…This is why Shkval is a dumb rocket that could not be guided…"

and

to the poster "Ed!", who wrote:
"…not care of a targeting solution…"

and

to the poster "joebuff", who wrote:
"…The Soviet supercavitating torpedoes were intended to have nuclear warheads, thus avoiding the need for much or any of an accurate firing solution. The Naval Underwater Weapons Center has reportedly developed a supercavitating torpedo that is able to use good target-homing technologies…"

(Continued)

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freefallingbomb November 18, 2009 at 11:55 pm

Part II :

Of course: Russian ammunition is too dumb to turn even a little bit. That's why it relies exclusively on nuclear warheads to hit any target.

"Guidance was nonexistent in initial designs, as the missile was intended for nuclear warhead delivery.
Later designs reportedly include terminal guidance and conventional warheads of 210 kg (460 lb).
The missile controls its direction using four fins that skim the inner surface of the supercavitation envelope. To change direction, the fin or fins on the inside of the desired turn are extended, and the opposing fins are retracted."

http://en.wikipedia.org/wiki/VA-111_Shkval#Design

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freefallingbomb November 19, 2009 at 2:49 am

Now not even I will open that new link.

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gsak November 20, 2009 at 1:19 am

I wonder if the Russians and Chinese are splitting rent on a lakefront house over on the shores of Lake Pend Oreille..

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Crazy Fox November 28, 2011 at 8:04 pm

Take a close look at the bow of the Russian submarine Sarov. It has a supercavitating bubble dome and two intakes running the long axis of the sub just forward of the con. A caterpillar is used to produce sea water cavitation bubble injection behind the dome.
The AIP is in fact a super compact steam generator (Fusion Cavitation) in tandem with a Kaluga KTP 7i condensing steam turbine. Suddenly a little diesel sub becomes the test bed for the new features of the Lada class boats. Other builders of subs doing similar research……gotta think outside the box and know what to look for.

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innocent October 9, 2012 at 8:12 am

Only Russia can do that science to Supercavitation

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Richard Dixon August 6, 2013 at 2:27 pm

Supercavitation……great for the future …..how about the Ghost project that Juliette Marine are doing in the navy yards of Virgina for US Navy trials ….supposed to use supercavitation twin torpedo like units on a catarmaran low slung body in between the two pontoons…..which are submerged to generate the supercavitation effect with forward facing wedge shaped propeller blades driven by a gas turbine jet engine in each torpedo pod….if it works the future is only just around the corner…..Richard Dixon. UK .TPD Studios.

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Abe L. D'Anger December 3, 2013 at 1:12 am

The Squall-111 was built into the Ribcraft and the Ribcraft was not filled with beer, as launched on a tuggy and then beaconed to the DDG67 in Aden.

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DualityOfMan November 19, 2009 at 11:58 pm

Sigh.

Yes, the Alfas were very, very fast. They were also loud, tiny, (1/2 the displacement of a Los Angeles class) and expensive.

Do you realize that cold war warships were equipped with anti-submarine missiles which dropped nuclear-tipped torpedoes? I imagine that one of those would do pretty well against an Alfa.

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freefallingbomb November 20, 2009 at 2:52 am

To the poster "DualityOfMan" :

You wrote: "Do you realize that cold war warships were equipped with anti-submarine missiles which dropped nuclear-tipped torpedoes?"

If the idea is only to sink enemy ships, then there are notoriously cheaper nuclear options to accomplish that than building submarines, yeah.

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