DCNS SMX-24 "Plug-and-Fight" submarine

Direction des Constructions Navales Services (DCNS) unveiled a concept for a new submarine named SMX-24 at the Euronaval 2008 show in Paris held on October 27-31, 2008.

Stealth aircraft have been compared to submarines, and there are similarities between the two. Both depend on a smooth outside mould line for survival and carry their weapons internally, restricted by the ability to cut holes in the skin.

But then DCNS unveiled its SMX-24 concept for an advanced submarine at the Euronaval show in Paris, and turned those presuppositions on their head.

SMX-24 is a concept for a submarine that would be in service about 2020. Its size and capability fall between today's biggest diesel-electric boats and the smallest nukes: the 3450-ton boat would have an all fuel-cell propulsion system, would be capable of 20 kt submerged and could stay underwater for 30 days. The core vessel would have interchangeable modules for weapons or special forces equipment. The stub wings carry tip-mounted propulsors for high speeds - allowing the central pumpjet to be sized for cruise - and fighter-like pylons for fuel tanks - above the wings on the model - and weapons

Click to expand...

http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckScript=blogScript&plckElementId=blogDest&plckBlogPage=BlogViewPost&plckPostId=Blog%3a27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3a746c0b19-3d2c-4f1f-ab90-b68183d15701&plckComment

The all-new SMX 24 submarine will incorporate ‘plug-and-fight’ modules enabling it to be reconfigured on demand to changing mission needs. DCNS has already identified 25 modules suitable for ‘plug-and-fight’ according to Navy needs. These include the submarine’s weapons (mines, missiles, etc.), sensors and performance-enhancing add-ons (offering greater speed, manoeuvrability or endurance, as the case may be). The modules will be housed at the wings level, in the sail and under the bridge. Different combinations of modules result in high-performance SMX 24 configurations with capabilities tailored to specific missions.

All DCNS-designed warships combine highly modular design and production. The SMX 24 offers new prospects and a new level of modularity. This concept sub exercise has enabled DCNS to identify both architectural and technological solutions meeting the future needs of client navies.

Increased modularity means a lower cost of ownership because ‘plug-and-fight’ modules can be shared by multiple submarines and crews. Note also that the SMX 24 requires a crew of just 22.

Click to expand...

http://www.digital-battlespace.com/2008/11/%E2%80%98plug-and-fight%E2%80%99-dcns-presents-next-generation-sub-at-udt-pacific/

Interesting concept. Thanks for posting.

-----JT-----

The external weapons carriage on a submarine looks like a strikingly dumb idea -- lots of drag and noise for remarkably little actual payload. The external payload would also be very exposed to shock damage.

External payload means less hull penetrations, and is the desired direction for the USN to go as well.

TomS said:

The external weapons carriage on a submarine looks like a strikingly dumb idea -- lots of drag and noise for remarkably little actual payload. The external payload would also be very exposed to shock damage.

Click to expand...

Yeah in the 1980s. But things are different now and in the future. Submarines are increasing using autonomous vehicles to do their dirty work. To operate these systems you either need very large, complex and risky ocean interfaces or external carriage requring no major pressure hull penetrations. Since the external payloads can be shapped for low drag and noise it becomes a rapid no brainer.

Aeroengineer1 said:

External payload means less hull penetrations, and is the desired direction for the USN to go as well.

Click to expand...

Yes and no. Outside the pressure hull, certainly, but not hanging out on pylons. That's a drag and flow noise generator for certain.

Abraham Gubler said:

Yeah in the 1980s. But things are different now and in the future. Submarines are increasing using autonomous vehicles to do their dirty work. To operate these systems you either need very large, complex and risky ocean interfaces or external carriage requring no major pressure hull penetrations. Since the external payloads can be shapped for low drag and noise it becomes a rapid no brainer.

Click to expand...

Sure, conformal carriage outside the pressure hull is a sensible idea. But stub wings and pylons are very bad ideas on subs.

From: http://www.aviationweek.com/aw/blogs/defense/index.jsp?plckController=Blog&plckScript=blogScript&plckElementId=blogDest&plckBlogPage=BlogViewPost&plckPostId=Blog%3a27ec4a53-dcc8-42d0-bd3a-01329aef79a7Post%3a746c0b19-3d2c-4f1f-ab90-b68183d15701&plckComment

But then DCNS unveiled its SMX-24 concept for an advanced submarine at the Euronaval show in Paris, and turned those presuppositions on their head.
SMX-24 is a concept for a submarine that would be in service about 2020. Its size and capability fall between today's biggest diesel-electric boats and the smallest nukes: the 3450-ton boat would have an all fuel-cell propulsion system, would be capable of 20 kt submerged and could stay underwater for 30 days. The core vessel would have interchangeable modules for weapons or special forces equipment. The stub wings carry tip-mounted propulsors for high speeds - allowing the central pumpjet to be sized for cruise - and fighter-like pylons for fuel tanks - above the wings on the model - and weapons.

Click to expand...

At 3450 tons it would be a quite small sub, intended for the littoral theatres. I think it would make sense to optimise hull space for other equipment ( sensors and the like) than large torpedo tubes and cary optional equipment outboard. Still, this design would restrict the roles this sub could be used in. Naval interdiction, for example, would not be an option.

Mission

The SMX-24 is a long-range, ocean-going conventional propulsion submarine (SSK) with an excellent payload capability.The design aims to optimise mission reconfiguration by combining maximum modularity and flexible features. The mission profile ranges from special operations to massive land strikes, in addition to the usual missions assigned to ocean-going SSKs, which is to say, attacks against enemy naval forces and fleet protection, both of which require significant anti-surface and anti-submarine warfare capabilities.


Cutting-edge technologies

The SMX-24’s systems benefit from promising concepts now emerging from DCNS’s R&D teams:

• High performance sonar featuring extra long flank arrays
  
• Advanced sensors and remotely-controlled unmanned vehicles
  
• New-generation weapons (land strike and anti-air missiles, hard-kill torpedoes, etc.)
  
• Augmented reality combat and platform management systems
  
• Energy production system featuring dual air/LOX fuel cells
  
• Superconductor technologies.

Modularity

The SMX-24’s innovative architecture offers four different types of modular areas which can be reconfigured easily and rapidly:

• cartridges masts in wings
  
• modular equipment bays
  
• side structures that can accommodate modules of various sizes and shapes
  
• a modular section for large modules.

The modules can be used to increase the boat’s payload (weapons, unmanned vehicles, sensors, special operation features, etc.) or performance (additional fuel, liquid oxygen, modular batteries, etc.).
More than 25 types of modules are currently available, with many more to come. The only limits on the SMX-24’s capabilities are the limits of human imagination.


Massive capabilities

Thanks to its extreme modularity and advanced technologies, the SMX-24 offers outstanding operational capabilities for its displacement:

• Storage space for 38 heavyweight weapons of various types
  
• Facilities for special operations teams of up to 18, including a 12-diver trunk, 2 drydock shelters and unmanned vehicles
  
• Excellent survivability thanks to improved sensors and stealth and a three-layer defences including weapons to knock out all types of platforms, decoys against all types of torpedoes and hard-kill torpedoes.
  
• Excellent mobility, sensors and communications and submerged endurance (i.e. without returning to
  periscope/snorkel depth) of up to 30 days.

Technical data

Displacement, surface: 3450 tonnes
Length overall: 88.8 meters
Diving depth: 350 meters
Beam overall: 26 meters
Maximum submerged speed: 20 knots
Submerged endurance: 30 days
Flank array area: 130 square meters
Complement: 22 to 31 (depending on configuration)

Source: DCNS Press Kit Euronaval 2008
http://www.dcnsgroup.com/files/dossier_presse/microsoft_word_-_press_kit_euronaval_2008_-_english_version.pdf

I'm not exactly an expert, but a square hull? Yeah, that promises lots of noise problems, and even without the wings and stores it'll be slower than a boat with a teardrop (or elongated teardrop) hull.

TomS said:

Sure, conformal carriage outside the pressure hull is a sensible idea. But stub wings and pylons are very bad ideas on subs.

Click to expand...

Yet real life naval architect submarine specialists are proposing it... Strange that.

Sure any extrusion from a perfectly streamlined hull, which BTW is not tear dropped but tubular, is going to create more drag. But sometimes you have to have these surfaces to do things like control the bearing and pitch of your vessel through the water. Especially with submarines that are not being designed for high speed sprinters (<21 knots) and can afford a bit more of a drag margin than your usual torpedo.

As to flow noise just like on a submarine’s sail, diving planes and control surfaces these can be managed. To assume that ‘conformal’ carriage is going to be OK for flow noise and hydroplanes are not is very ignorant. Noise is not the same as low drag in a much less dense liquid. The conformal arrangement will have to be very precise to avoid turbulence. But in a fighter aircraft creating a low drag slipstream over the aircraft surfaces is a very different thing.

MihoshiK said:

I'm not exactly an expert, but a square hull? Yeah, that promises lots of noise problems, and even without the wings and stores it'll be slower than a boat with a teardrop (or elongated teardrop) hull.

Click to expand...

The hull isn’t square it has straight sides but they are not joined by right angles. Nor is the bow part of a square. As long as the hull form leading to the straight surfaces does not create burbles and the like then the water won’t make any more noise flowing down a straight surface as a curved one. There can even be quite a few acoustic advantages from straight sides.

To base an acoustic analysis on this submarine by simply comparing it’s rough looks with a more well known submarine is just misleading.

What about going for double hull construction with the weapons between the outer "faired" hull and the pressure hull, in much the same way as the Los Angeles class SSN have their Cruise Missile VLS?

I know that British subs carried torpedo tubes external to the pressure hull during WWII, although in a not particularly hydrodynamic way?

Thanks for the explanation Abraham. Since this is a concept of a submarine for the year 2020, are there any new materials on the horizon that could be practical for submarine use in the next ten years that could further absorb vibration and dampen water flow noise over materials used in current designs?

JohnR said:

What about going for double hull construction with the weapons between the outer "faired" hull and the pressure hull, in much the same way as the Los Angeles class SSN have their Cruise Missile VLS?

Click to expand...

Why? You add the complexity of somehow getting between the ocean and the outer hull just so the UVs are "faired" when they can be perfectly fine outside all the hulls, hitching a ride from the submarine. The advantage of taking a UV inside the pressure hull is so they can be maintained, recharged, reloaded etc in conventional manners. The cost of that to the submarine is prohibitive compared to designing the UV to be sustainable while outside the pressure hull.

Triton said:

Thanks for the explanation Abraham. Since this is a concept of a submarine for the year 2020, are there any new materials on the horizon that could be practical for submarine use in the next ten years that could further absorb vibration and dampen water flow noise over materials used in current designs?

Click to expand...

There are lots of materials and new technology being developed to reduce vibtation and improve water flow, also materials to absorb noise.

Abraham Gubler said:

TomS said:

Sure, conformal carriage outside the pressure hull is a sensible idea. But stub wings and pylons are very bad ideas on subs.

Click to expand...

Yet real life naval architect submarine specialists are proposing it... Strange that.

Sure any extrusion from a perfectly streamlined hull, which BTW is not tear dropped but tubular, is going to create more drag. But sometimes you have to have these surfaces to do things like control the bearing and pitch of your vessel through the water. Especially with submarines that are not being designed for high speed sprinters (<21 knots) and can afford a bit more of a drag margin than your usual torpedo.

As to flow noise just like on a submarine’s sail, diving planes and control surfaces these can be managed. To assume that ‘conformal’ carriage is going to be OK for flow noise and hydroplanes are not is very ignorant. Noise is not the same as low drag in a much less dense liquid. The conformal arrangement will have to be very precise to avoid turbulence. But in a fighter aircraft creating a low drag slipstream over the aircraft surfaces is a very different thing.

Click to expand...

You know, we may not agree, but calling someone ignorant because they disagree is exceptionally rude. I'm really getting tired of the insults, especially since I haven't been directing any at you. Can we have a civil conversation please, without the put-downs?

I've been working on and around shipbuilding programs for about 15 years now. I'm not a naval architect, but I have more than a passing exposure to submarine design. And this is a very odd design. The fact that professional designers put forward the design is NOT proof that it's a good idea -- I've seen quite a few very ill-conceived designs put forward by ostensibly professional designers. And of course, it's fairly common in this business to put forward designs that aren't really intended for production but are used to draw attention or even just to give engineers something different to work on. Remember Lockheed's CHARC concept? I think SMX-24 is similar -- a study concept that looks enough different from a conventional sub to generate buzz but not really intended to be a finished design. The history of the SMX-2x series over the past few years reinforces that, in my opinion. In 2004, they had SMX-22, with a mother sub and two smaller baby subs strapped alongside. That wasn't a design approach likely to make sales, but it did generate media coverage, which I suspect was its purpose. It's worth noting that SMX-24 does not appear on the DCNS web page any more, while the Andastre design derived from the much more conventional SMX-23 does.

ON the technical front, yes, hydroplane drag can be "managed." But designers only do so because they can't find any other solution to the submarine ship control problem. There have been many proposals that would eliminate or sharply reduce both planes and sails because of their contribution to drag and noise (especially once people figured out their contribution to the blade-rate signature). Both features remain because the alternatives just don't work (not yet, at least).

The payload-carrying wings on the SMX-24 model are a different kettle of fish from hydroplanes for ship control. They don't seem to serve any necessary purpose. The payloads they carry could just as easily be adding in the form of fairings mounted to the hull itself at much lower cost in terms of wetted area. And wetted area matters a lot, even at 20 knots. If this were a midget sub traveling at 5-10 knots, I wouldn't be so critical, but for a sub that intends to make 20 knots with a relatively long range, anything that detracts from streamlining is going to deliver a noticeable performance hit (hence the extreme streamlining efforts on the GUPPY submarines, for instance), and it's hard to see how these won't do that. I'm especially skeptical of the fitting of separate pods close to each other under the "wing." That's likely to cause odd interactions between the flows coming off each pod, which is a prime opportunity for drag and noise creation.

Abraham Gubler said:

Why? You add the complexity of somehow getting between the ocean and the outer hull just so the UVs are "faired" when they can be perfectly fine outside all the hulls, hitching a ride from the submarine. The advantage of taking a UV inside the pressure hull is so they can be maintained, recharged, reloaded etc in conventional manners. The cost of that to the submarine is prohibitive compared to designing the UV to be sustainable while outside the pressure hull.

Click to expand...

TomS said:

The external weapons carriage on a submarine looks like a strikingly dumb idea -- lots of drag and noise for remarkably little actual payload. The external payload would also be very exposed to shock damage.

Click to expand...

Aeroengineer1 said:

External payload means less hull penetrations, and is the desired direction for the USN to go as well.

Click to expand...

Abraham, I made my points in response to the above two posts, I was suggesting that if submarines were built in the same manner as many Russian/Soviet boats double hulled boats, weapons could be emplace between the outer hull and the pressure hull, this would answer both of these points, you could maintain the hydrodynamic shape of the hull and avoid penetrating the hull.

I freely admit that I am an interested amateur and not an industry expert, but everything I have read in the past indicates this is proposal does not make sense. The quieting programs of the US and Royal Navies, assiduously removed any and all hull projections from their submarines to ensure the quietest boats possible.

Then the US navies experiments resulting in the Albacore demonstrated the optimal shape for a high speed submarine, which has been almost universally adopted, with modifications and refinement, by the worlds navies. The fitting of a single screw has also been a virtually universal.

Therefore fitting big wings with propellers on the end seems to go against everything I have previously read, they may have been proposed by naval architects but so was other warships of the past which proved dead ends; the Greek Quadermarine, the torpedo ram, HMS Captain, and the Circular battleships.

May I add to TomS's comment that I find your responses both condescending and abrasive, and unnecessary of a Forum that I regard as being to improve my knowledge and ultimately for fun.

And may I close by saying that much of the information I have stated is gleaned from such authors and Norman Friedman and DK Brown, not by you who as a writer I have never heard of. Just because you say so doesn't make it so.

I suppose there are some interesting takeaways from the design;


1. Having a center pressurized core section, followed by what amounts to a pair of faired side saddle wet bays like a soviet double hull can provide some interesting options, provided this is a true all electric vessel that can afford to isolate the main motor assembly with the pumpjet at the end of a long truss assembly that resembles a spine in the wet bay...

2. As evidenced in this thread, there is going to be a long tradeoff argument over faired modules or externally hung stores. If there is a preference for littoral waters, to a lesser degree there is preference on speed, on less vertical height, and some emphasis on reducing length (at least regarding a turn radius). This generally forces a designer to go wide, either through parallel double hulls, wide secondary hulls like the soviets, or wings to hang stores. If it is reasonable based on expected missions to be able to dump most of the systems that involve expendables, then wings aren't a horrific idea.

3. The assumption of a LOx fuel cell system brings with it all sorts of interesting possibilities. With the refrigeration systems required for LOx, you gain the ability to deal with LN2, which leads to high temperature superconductors for power handling and propulsion motors, which are now entering the commercially viable stage. There are other secondary tricks as well, since if you have significant LN2 tankage, you might be able to pull off a SMES system for power storage provided you could get the external magnetic signature down. Though if EESTOR turns out to be real, I think every major military contractor will be lining up for those batteries instead. An interesting side question is they noted a dual air/LOx system. Is this because it's still unreasonable to operate a LOx ASU from a snorkel at tolerable efficiencies and power requirements?


What makes me wonder is why they didn't try some other tricks considering the assumptions given? One thing that comes to mind is an aircraft BWB or manta shape? Wing sections thick enough to store one flat layer of rectangular modules that could accommodate most common torpedoes and missiles, while still retaining the ability to hang underwing stores?


There would certainly be one extreme option available if length concerns are not large, taking the concept of a core features skeleton to it's logical conclusion. Have a bow/forebody/main sensor section connected via variable length truss/spine leading to a central pressurized core barrel section, followed by another variable length truss/spine leading to the stern/afterbody/rear sensor section. Have a body encircling propulsor ring around the outer diameter of the center core section (probably forward of the sail). Whatever module you want/need, you hang on the spine like fish steak slices on a pole, changing the length of the spine so it all seals together into one continuous body. Because the modules are mostly neutrally buoyant, it isn't hard to simply expand the spine and release the module and have float it away.

TomS said:

You know, we may not agree, but calling someone ignorant because they disagree is exceptionally rude. I'm really getting tired of the insults, especially since I haven't been directing any at you. Can we have a civil conversation please, without the put-downs?

Click to expand...

There is nothing personal in my criticism of your commentary. Just a strong opposition to the simple and inaccurate explanation you have given to this design. As you are no doubt well intentioned and bright I would say you are making logical assumptions from a limited knowledge base. Therefore I credit it to ignorance the mistakes in your assumptions because clearly that’s where it’s from.

By having straight sides the DCNS boat is not likely to make more noise and the wing mounting of UUVs has a range of advantages despite an increase in drag. Properly faired straight surfaces as in this DCNS boat do not create more turbulence than circular shapes. Most submarines look circular for completely different reasons like pressure resistance and reduced surface area. If the DCNS boat was a brick shape with sharpe angles you would have a point but it isn’t and you don’t.

With mounting conventional torpedo shaped UUVs using wing pylons enables you avoid the problems of conformal blistering. Especially after the UUV has been deployed and what was once a streamlined blister now becomes a non streamlined space generating lots of turbulence. The solution to this is to design UUVs that are shaped like remoras and don’t need any blistering to attach them in a streamlined way. As in the Forward Pass type UUVs. But if you want to work with what you’ve got, like the French here, then wing carriage is the way to go for external mounting,

JohnR said:

May I add to TomS's comment that I find your responses both condescending and abrasive, and unnecessary of a Forum that I regard as being to improve my knowledge and ultimately for fun.

And may I close by saying that much of the information I have stated is gleaned from such authors and Norman Friedman and DK Brown, not by you who as a writer I have never heard of. Just because you say so doesn't make it so.

Click to expand...

I have made no statements referencing who I am or aren’t to support my comments. Just reasoned facts to support conclusions. You can continue to make uninformed comments and I will continue to provide a factual response where it lies within my knowledge base. If you don’t enjoy it then I suggest you make your comments in an area that you actually know what you are talking about.

You persist in trying to say that double hulls are a solution to the UUV mounting dilemma. But what is between those double hulls? Water. While interfacing a UUV between an outer hull into the wet space outside the pressure hull may enable carriage without additional drag it doesn’t provide the ability for human’s to maintain, recharge, etc said UUV. Considering the complexity of such a hangar, interface design, with the minimal payoff (ie no maintenance) it’s no wonder no one is pursuing such a design.

I'm pretty sure that the pods, no matter how well designed, are going to have SOME acoustic penalty. That being said, I gather that the operational concept is to drop the fuel tanks and release the UUVs prior to entering the combat zone. That would leave the hull clean. The need to enter the action area very slowly and any odd hydrodynamics from the 'wing' would be a trade-off perhaps, but it allows everything to launch (or be pickled) at once. Even the trade-off argument can be turned around a bit. That is, "dropping" a UUV from the 'wing' is likely to have a far smaller acoustic signature than launching from a torpedo tube or opening big hatches.

One rather far fetched rationale pops into my mind...The external carriage also gives the UUVs a tiny bit of distance away from the pressure hull in the event their ordinance or (less likely) fuel were detonated. This is not likely to do much good but perhaps every little bit helps. Sidon and Kursk come to mind.

As an aside, the slab sided profile of the vessel indicates it is almost certainly double hulled as the pressure hull needs to be a cylinder.

Brickmuppet said:

One rather far fetched rationale pops into my mind...The external carriage also gives the UUVs a tiny bit of distance away from the pressure hull in the event their ordinance or (less likely) fuel were detonated. This is not likely to do much good but perhaps every little bit helps. Sidon and Kursk come to mind.

Click to expand...

I have seen a video somewhere; can't remember if it was on TV or on the Net, which showed a concept of a submarine which had "mini" subs which faired into the mothership and separated off to attack a target. Has anyone else seen it, and can find additional details.

View of french modular submarine concept of SMX family
Regard

Where's the Flying Sub?

TomS said:

Abraham Gubler said:

Yeah in the 1980s. But things are different now and in the future. Submarines are increasing using autonomous vehicles to do their dirty work. To operate these systems you either need very large, complex and risky ocean interfaces or external carriage requring no major pressure hull penetrations. Since the external payloads can be shapped for low drag and noise it becomes a rapid no brainer.

Click to expand...

Sure, conformal carriage outside the pressure hull is a sensible idea. But stub wings and pylons are very bad ideas on subs.

Click to expand...

JohnR said:

What about going for double hull construction with the weapons between the outer "faired" hull and the pressure hull, in much the same way as the Los Angeles class SSN have their Cruise Missile VLS?

I know that British subs carried torpedo tubes external to the pressure hull during WWII, although in a not particularly hydrodynamic way?

Click to expand...

One has to wonder why they don't have a single pylon mounted flush with the hull in order to hold a pod. Such a multi-hull design could remove the difficulty in reconfiguring a "faired" hull for different tasks (as the second hull would be stand alone, manufactured separately and not conformal to the pressure hull). One has to wonder if there is some maneuvering purpose (related to the wing mouned props) or anticipated sensor system involved.

The move toward smaller, multi-purpose submarines is also interesting. It makes sense if you need a rapid nuclear retalition or tactical land based strike or anti-ship or anti-pirate or short range anti-aircraft or commando support or surveillance duty ship rather than being focussed soley on overwhelming the defenses of another superpower's cities or battlegroups.

DCNS SMX-24 brochure

Source:
http://blog.daum.net/_blog/BlogTypeView.do?blogid=0U9O8&articleno=39&categoryId=10&regdt=20100803124221#ajax_history_0