Modular multi-mission submarine?

[covert_shores]

Are there any concepts for that? The threads about transport submarines made me think.

Imagine a mid sized submarine which is two pressure hulls, say 40m long (so overall length about 50-60m). They are widely spaced so that additional mission modules can be dropped into the middle. Connection sections would be needed, and swapping modules would take days or weeks but could be done without dry docks. With modern electro-optical masts the sail could also be part of the module system.

Modules would include torpedo rooms (with or without reloads depending on configuration), VLS, accommodation, masts, bouys, lock out chambers, dry deck shelters, wet storage, dry storage, towed arrays, larger sonars, and blank sections. Modules would be largely self contained including bouyancy considerations etc.

Main hulls would include sonar (modest, conformal arrays?) , comms, command, crew accommodation, messes, galley, batteries, propulsion (twin screw I'd assume, like Typhoon). Control and buoyancy and trim needs (supplemented in modular fit if necessary). I'D also add thrusters and wheels. But no masts or weapons.


Am I mad or dumb?

 

[Grey Havoc]

The Vickers Piranha small sub family and the more recent USN KAPPA unmanned project have shades of what you're talking about.

 

[covert_shores]

Thanks!

kappa is very interesting, I wonder what size and capability it'd have?

I added a bit of info to the piranha thread. Nice design but not so much configurable once built, more like build choices (?)

 

[shedofdread]

Do bare in mind that as the hull design changes (length etc), things like the required hydroplane size will alter. As also will the hydrodynamic qualities which would all need modelling and the further effects thereof understanding.

 

[Moose]

This thread may interest you.

 

[Rickshaw]

The connectors between the various hull sections would be difficult to engineer. They would remain the weak points and prevent diving to the same depths that a monolith like hull would be able to do. Might be easier to design a normal submarine with a flat back onto which modules could be attached as required. Essentially you need to keep all habitation within the one structure on a submarine or accept that there cannot be any connection between the sections.

 

[covert_shores]

The NNEMO1 has a lot in common which the hull configuration I was thinking of although it's much bigger.

Connections between multiple hulls can be made strong enough I think. The Typhoon, UNIFORM, Losharik and Dutch Dolfijn classes for example. All submarines have multiple 'holes' in their pressure hulls which need to be sealed before submergence, this is just increasing the number. I imagine swapping sections and ensuring all the connectors are pressure-tight would take several days at least and probably involve divers. But seems possible.

I am now imagining a boat with two 6m diameter hulls side by side with 6.5m between them and 6m diameter modules added in the center. Tis depth allows for VLS, although the casing might have to be raised. From the op the core submarine is actually shaped like an H with the connectors to the modular sections both fore and aft of the cross-element. The sail and diver lock-out could also be incorporated into the cross-element.

 

[shedofdread]

If I read you correctly, that would be a rather 'draggy' configuration. Further problems would include structural issues and flow noise. I think I ought to leave it at that. Not saying you couldn't have a modular sub but there are challenges...

 

[Arjen]

Connections between multiple hulls can be made strong enough I think. The Typhoon, UNIFORM, Losharik and Dutch Dolfijn classes for example. All submarines have multiple 'holes' in their pressure hulls which need to be sealed before submergence, this is just increasing the number. I imagine swapping sections and ensuring all the connectors are pressure-tight would take several days at least and probably involve divers. But seems possible.

The connections between the multiple pressure hulls of the Dolfijn submarines were all welded, I don't know about the other classes. I think the forces exerted on hull connections are considerably bigger than those on a hatch/hull interface. They are also of a fundamentally different nature. A hatch usually gets pushed onto its seat - water pressure actually helps to create a watertight seal. Hull connections are subject to bending, stretching, shearing forces.

I would always expect a non-permanent connection between pressure hulls to be weaker than a properly built permanent one.

 

[covert_shores]

So a better analogy for the connections are the ones on Dry Deck Shelters (DDS) currently. Maybe they are welded?

And there would be two types if connection, non-penetrative (sorry!!!) and ones that penetrate the pressure hulls for hatches, pipes and cables. Just like DDS in fact. The non-penetrative ones would deal with the load, or at least minimize it.

Dry SDVs/subs are often attached to a hatch for transit (back to WW2 when Italians and Japanese did this) and that must be even harder. Modern examples are ASDS, DSRV, Losharik to mother-sub, Russian escape capsules.

 

[covert_shores]

not deeply thought out:

Main hulls are about 5.5m diameter, just big enough for two decks. The central modular hulls are maximum of 4.5m which is limit for C-17. DDS is less than 3m diameter. Both fore and aft modular sections are up to 20m long. Overall length approximately 50m. Note that use of modern sonar arrays saves a lot of space in the nose.

VLS would have to either be angled or involve a raised central spine casing. Sail is also partly modular.