SSN (X) - Seawolf Redux or something far larger?

[Sferrin]

Any ideas to have titanium over HY-80? Maybe some defense spending to get better titanium handling facilities can be folded into aerospace projects later.

As tough as it is to get titanium for aerospace, the notion of titanium submarines is absolutely laughable.

 

[chimeric oncogene]

the notion of titanium submarines is absolutely laughable

Well, yes, but the Soviets actually built a whole class of titanium attack submarines.
Dunno how they welded the ten meter pressure hull segments of the alfas, but for smaller fittings they had these giant pressure chambers.
Insane expense but it's doable, we know it's doable because it's been done.

Now of course the big question is "why?", and ultimately this is a cost-effectiveness thing, but if the analysis suggests a deeper-diving submarine, and HY-120 or what have you is not up for the job or encountering issues, then Titanium is probably not a terrible alternative; probably not worse than metal matrix composite or ceramic or whatever (maybe MMC might be easier to work, but it's a more exotic material and there seems to be less experience with it). Other composite submarines are probably possible but have a bad rep these days.
In actuality I guess you would take the L and accept the shallower test depth and spend the money on more reasonable things, but if we're looking at alternative materials, Ti is probably one option to consider.

 

[Scott Kenny]

I would argue that the reason all western subs following SSN-21 have shallower test depths is because everybody went all-in on littoral warfare in the early 90's, and we're still paying the price for that IMO (I was a vocal opponent at the time via my USNI involvement).

Disagree. Virginias had to be much cheaper than Seawolf.

The motto should "be run silent, run shallow" if we're being honest.

That motto comes from a book about WW2 subs, where "deep" was "below ~200ft"

Any ideas to have titanium over HY-80? Maybe some defense spending to get better titanium handling facilities can be folded into aerospace projects later.

I dunno, you work with titanium very differently for aerospace than for submarines. Most aerospace stuff is sheets or small blocks, not a huge sheet some 120mm thick and multiple meters in each direction.

It's possible that you could cut those submarine-sized sheets into blocks for aerospace.

And while you can machine titanium in regular atmosphere, you cannot weld thick titanium except in an inert atmosphere. Which means an entire factory floor that's filled with argon or nitrogen and the welders working in what amounts to scuba gear.

 

[Sferrin]

Well, yes, but the Soviets actually built a whole class of titanium attack submarines.

Yes, that's been talked about here. And the Alfas weren't the only class. The Sierras were also as well as the Mike and Papa one-offs.

Now of course the big question is "why?", and ultimately this is a cost-effectiveness thing, but if the analysis suggests a deeper-diving submarine, and HY-120 or what have you is not up for the job or encountering issues, then Titanium is probably not a terrible alternative;

It is if you don't have it. The USSR/Russia has a lot of titanium. The US less so. (That's why Blackbird titanium had to come from Russia.)

 

[publiusr]

And while you can machine titanium in regular atmosphere, you cannot weld thick titanium except in an inert atmosphere. Which means an entire factory floor that's filled with argon or nitrogen.

That's why I brought it up--didn't we have someone who worked on NASP who said he needed those facilities?

My plan was to do a Radar/Sparky and get Trump or someone to sign on for facilities needed for titanium subs--then have it go to aerospace later.

If you asked for those handling facilities for space DC would say no. For subs, maybe yes.

You have to be sneaky these days to get anything funded.

 

[Sferrin]

That's why I brought it up--didn't we have someone who worked on NASP who said he needed those facilities?

My plan was to do a Radar/Sparky and get Trump or someone to sign on for facilities needed for titanium subs--then have it go to aerospace later.

If you asked for those handling facilities for space DC would say no. For subs, maybe yes.

It's like the kid on Christmas asking for a dragon. He just doesn't understand dragons aren't real.

 

[tychosis]

The other point is that it doesn't really gain you a whole lot.

Yeah, it doesn't. I mentioned previously, you don't gain much while you're exposing yourself to exponentially greater risk.

Sure, there's the DSC--but no submarine array has the baseline length to localize anything down there. Everything down there is LF--*very* low--so the best you're going to be able to do is say "there's something in that general direction maybe 100 miles away, maybe 1000 miles away." Generally the only way you're able to localize anything down there is with multiple stations a great distance from each other.

It's useful for surveillance but has little real tactical use. As I mentioned in another tangentially-related post, I think people have been reading a bit too much Clancy haha.

 

[Foo Fighter]

The mechanism behind those composite armor is that they are brittle and eat a lot of energy in the process of shattering. Terrible characteristics for a submarine hull.

I was not thinking Dorchester armour as is, it is designed for a different purpose but, something of a layered composite.

 

[Yellow Palace]

Oh I thought you meant a declassified figure.

Sadly not. Unfortunately, it would appear that the Royal Navy Submarine Service would prefer the fact that it has submarines to be classified, never mind any information about them.

If there is a difference between diesel and nuclear practice for hull factor of safety, that tells an interesting story in its own right.

If I was feeling particularly rude, I'd ask how many authors of that study had served on submarines.

I'm not sure that criticism is entirely valid when considering an NR-1 replacement. Almost the only similarity between the operational requirements for that mission and those for a fleet submarine is that they both take place underwater.

The study is linked and discussed in this thread, which is probably a more suitable place for discussion of ultra-deep non-combatant submarines.

Disagree. Virginias had to be much cheaper than Seawolf.

Unless you're very lucky with technology, 'cheaper' almost invariably means 'less capable'. Which may be a valid trade, of course, and there's some reason to think the SEAWOLF/VIRGINIA change did combine with some big technological improvements.

 

[tychosis]

Unless you're very lucky with technology, 'cheaper' almost invariably means 'less capable'.

While this is often the case, that convention really doesn't hold up any more once you're looking at the timeframe between SW development and build and VA development and build. The rise of COTS allowed us to abandon many exorbitantly expensive (and inferior) legacy systems.

 

[whatismoo]

I was not thinking Dorchester armour as is, it is designed for a different purpose but, something of a layered composite.

Modern composites are all layers. Also Dorchester/Chobham/Burlington is non-explosive reactive armor made from multiple layers of sandwiches of metal plates with rubber or similar between them, not ceramics.

 

[Sferrin]

While this is often the case, that convention really doesn't hold up any more once you're looking at the timeframe between SW development and build and VA development and build. The rise of COTS allowed us to abandon many exorbitantly expensive (and inferior) legacy systems.

No such thing as a COTS submarine hull.

 

[Foo Fighter]

Ceramic composites. Definitely part of the Dorchester/Chobham blend.

 

[MihoshiK]

Ceramic composites. Definitely part of the Dorchester/Chobham blend.

There's lots of ceramic composites. Just because it shares the same name does not mean it will be useful for another application.

Armor ceramics are hard and brittle, designed to erode anything moving through them.

This does not mean they're going to be useful for cyclic load bearing applications like submarine hulls.

 

[tychosis]

No such thing as a COTS submarine hull.

True, but the hull itself is a relatively insignificant contributor to the overall cost of a submarine compared to everything inside the hull.

 

[Sferrin]

True, but the hull itself is a relatively insignificant contributor to the overall cost of a submarine compared to everything inside the hull.

Most of which isn't COTS available either.

 

[tychosis]

Most of which isn't COTS available either.

Much more than you'd think. COTS isn't just the servers and electronics everyone thinks of, it includes industrial equipment like motors, pumps, accumulators, etc etc. The amount of bespoke hardware onboard a submarine has declined significantly over the years.

 

[Sferrin]

Much more than you'd think. COTS isn't just the servers and electronics everyone thinks of, it includes industrial equipment like motors, pumps, accumulators, etc etc. The amount of bespoke hardware onboard a submarine has declined significantly over the years.

Probably to its detriment. How durable and reliable is COTS equipment compared to made-for-the-job?

 

[whatismoo]

Ceramic composites. Definitely part of the Dorchester/Chobham blend.

There's lots of ceramic composites. Just because it shares the same name does not mean it will be useful for another application.

Armor ceramics are hard and brittle, designed to erode anything moving through them.

This does not mean they're going to be useful for cyclic load bearing applications like submarine hulls.

I don't want to get too far off topic, but there's been no indication that Chobham/Dorchester/Burlington has any ceramics in the mix. Ceramic-composites got a lot of press due to the Soviet use, but as far as can be told from the available sources, their presence in western "Box Tank" era armor packages is spurious.

 

[tychosis]

Probably to its detriment. How durable and reliable is COTS equipment compared to made-for-the-job?

It all goes through the same EQT testing, so it's just as durable.

It's also more reliable--given that if the Navy contracts a vendor to deliver bespoke hardware, they can deliver substandard equipment because Navy has no other option. Products that other end-users rely upon are generally going to meet a higher standard because the market and industry has demanded it.

I've seen it firsthand. I spent a few years in the development, integration and deployment of the tech refresh to the old Raytheon transmit group on VABLKI/II. The original system was awful, mostly just recycled BSY-1 trash. Raytheon delivered it with the assumption that they'd be asked to update it within a few years. (That day never came, and PMS450 pretty much just kicked them out of the submarine sonar world.)

 

[Yellow Palace]

True, but the hull itself is a relatively insignificant contributor to the overall cost of a submarine compared to everything inside the hull.

And everything outside the hull, for that matter. Quite a lot of things that aren't in the people tank.

Probably to its detriment. How durable and reliable is COTS equipment compared to made-for-the-job?

You'd be surprised. Some years ago I was told by a specialist shock engineer that virtually everything you can buy off the shelf at your local electronics retailer will pass the lowest levels of shock testing required for naval equipment. That's actually a less demanding criterion than surviving being in the back of a truck on the way to the store.

 

[Foo Fighter]

There's lots of ceramic composites. Just because it shares the same name does not mean it will be useful for another application.

Armor ceramics are hard and brittle, designed to erode anything moving through them.

This does not mean they're going to be useful for cyclic load bearing applications like submarine hulls.

I never said Chobham or Dorchester should be used for submarine hulls. A combination meterial with different layers combined to creat the idea for the task.

 

[TomS]

I never said Chobham or Dorchester should be used for submarine hulls. A combination meterial with different layers combined to creat the idea for the task.

I think it's unlikely, or at least would be exorbitantly expensive.

The main thing that I see an obstacle is differential compression. Submarine hulls actually change diameter noticeably under pressure. I suspect trying to accommodate that with layers of dissimilar materials would result in either cracking or separating the layers.

 

[Vepr157]

A combination meterial with different layers combined to creat the idea for the task.

Composites (e.g., fiberglass, carbon fiber) are in theory good materials for submarine pressure hulls but have their own serious issues (see Titan submersible disaster). Welding and inspecting a steel hull made from homogeneous material is hard and expensive enough. So a material with layers would be a manufacturing and inspection nightmare.

 

[tychosis]

You'd be surprised. Some years ago I was told by a specialist shock engineer that virtually everything you can buy off the shelf at your local electronics retailer will pass the lowest levels of shock testing required for naval equipment. That's actually a less demanding criterion than surviving being in the back of a truck on the way to the store.

Yeah it's that long-term low-intensity vibe that's the worst. The problems it causes can often be cryptic and intermittent.

Honestly--it's generally assumed that things are going to break during high-intensity shock testing, we're primarily concerned that things break in a safe manner.

 

[Yellow Palace]

Honestly--it's generally assumed that things are going to break during high-intensity shock testing, we're primarily concerned that things break in a safe manner.

Broadly speaking - you probably know this, but some may not - there are three standards of performance expected after shock:

• Remain captive (i.e. don't fly off and do more damage)
• Able to return to function after shock
• Remain functioning through shock

The level of shock that's applied then varies depending on the type of vessel and where in the vessel the equipment is located.

Heretical thought: we've discussed deeper depths. But what about shallower ones? As it becomes possible to offload more of the capability of a combatant onto offboard systems, does a submarine need to be capable of deep diving? It was accepted a long time ago that putting the extreme performance into torpedoes made sense, so why not do the same with sensor platforms?

Following that to its logical conclusion, does it need to be capable of diving at all - if you go fully in the direction of offboard systems, those can be deployed perfectly well from the surface.

I'll now retreat into my (deeply buried, MOP-defeating) bunker.

 

[tychosis]

Heretical thought: we've discussed deeper depths. But what about shallower ones? As it becomes possible to offload more of the capability of a combatant onto offboard systems, does a submarine need to be capable of deep diving? It was accepted a long time ago that putting the extreme performance into torpedoes made sense, so why not do the same with sensor platforms?

When you think about it, we're *always* operating pretty shallow. Compared to total water depth, we're in a paper-thin slice just at the top. As mentioned several times in this thread, there's just no real reason to go much deeper than we already do.

Too shallow though, and you have to worry about people running you over. And being surfaced where everyone can see you... well that kinda defeats the purpose of a submarine. You're sometimes doing things you don't want others to know you're doing, in places you really shouldn't be.

The level of shock that's applied then varies depending on the type of vessel and where in the vessel the equipment is located.

I've often (somewhat grimly) joked that the most extreme environmental quality testing must be for salvage purposes, because us squishies probably won't survive it.

 

[Yellow Palace]

And being surfaced where everyone can see you... well that kinda defeats the purpose of a submarine.

That's the point, yes... if you're putting the performance into the offboard platforms, do you really need to be a submarine at all? Mostly stirring the pot of course. There are certainly things you can do with a submarine that you could never do with a surface ship. And some things that are easier without that pesky free surface in the way.

But launching and recovering AUVs dragging towed arrays around a task group? That barely needs the surface ship to be painted grey, much less a submarine.

I've often (somewhat grimly) joked that the most extreme environmental quality testing must be for salvage purposes, because us squishies probably won't survive it.

How deep will a submarine go? Right to the bottom, if you let it.

 

[Scott Kenny]

I'm not sure that criticism is entirely valid when considering an NR-1 replacement. Almost the only similarity between the operational requirements for that mission and those for a fleet submarine is that they both take place underwater.

And are (relatively) quiet.

Unless you're very lucky with technology, 'cheaper' almost invariably means 'less capable'. Which may be a valid trade, of course, and there's some reason to think the SEAWOLF/VIRGINIA change did combine with some big technological improvements.

Smaller hull with half the non-nuclear long-lead items (torpedo room). Less powerful reactor than Seawolf, less total speed (IIRC).

No such thing as a COTS submarine hull.

The big one was sonar and FCS computers. ARCI, Acoustic Rapid COTS Insertion. Electric motors are electric motors.

Heretical thought:

*starts handing out torches and pitchforks*

we've discussed deeper depths. But what about shallower ones? As it becomes possible to offload more of the capability of a combatant onto offboard systems, does a submarine need to be capable of deep diving? It was accepted a long time ago that putting the extreme performance into torpedoes made sense, so why not do the same with sensor platforms?

Following that to its logical conclusion, does it need to be capable of diving at all - if you go fully in the direction of offboard systems, those can be deployed perfectly well from the surface.

Well, as long as the sub itself is the sensor platform, you're going to need "greater than 800ft".

Rapid transit while submerged also requires depth. A hull optimized for submerged operations is quite limited in surfaced speeds, and you're going to cavitate like a fool if you're shallow.

Basic hiding from surface ships means lurking down at or below 300ft.

 

[BlackBat242]

Unless you're very lucky with technology, 'cheaper' almost invariably means 'less capable'. Which may be a valid trade, of course, and there's some reason to think the SEAWOLF/VIRGINIA change did combine with some big technological improvements.

Then there are the changes since then that have been incorporated in successive blocks - water-backed large-aperture bow array instead of air-backed spherical bow sonar array, multiple-round launch canister instead of individual VLS cells, and so on.

 

[bobbymike]

https://www.navalnews.com/naval-new...-pacific/?mc_cid=bd325f8ecd&mc_eid=307947a252

 

[Grey Havoc]

Disagree. Virginias had to be much cheaper than Seawolf.

Though they ironically actually ended up being more expensive!

 

[Firefinder]

Though they ironically actually ended up being more expensive!

Only in the later marks as new things and refinements got added.

Plus inflation is a bitch.

Speaking of project revolver...

Do wonder if they will pull out the data for the Torp Auto reloading system that would have increased the later 688 class from 24 to 37 weapons for the Torp tube.

View: https://www.youtube.com/watch?v=4CiemhuXZpc

 

[Scott Kenny]

Though they ironically actually ended up being more expensive!

Only after a lot of upgrades.

 

[TomS]

Only in the later marks as new things and refinements got added.

Plus inflation is a bitch.

Speaking of project revolver...

Do wonder if they will pull out the data for the Torp Auto reloading system that would have increased the later 688 class from 24 to 37 weapons for the Torp tube.

View: https://www.youtube.com/watch?v=4CiemhuXZpc

Despite the name, it seems to be just developing a multi-round insert for standard tubes. More like Project Pepperbox if you ask me.

 

[Scott Kenny]

Despite the name, it seems to be just developing a multi-round insert for standard tubes. More like Project Pepperbox if you ask me.

Sorta.

As I understand it, Project Revolver is still only firing one mini-torpedo at a time, instead of volleying the entire load. Which does save you a whole lot of time on the reload for however many mini torpedoes are in the insert. Then it's the usual ~12min** to back-haul the empty insert and load whatever you're going to stuff in there next.

** Yes, it really does take that long to safely stuff a new fish in the tube.

 

[Grey Havoc]

Only after a lot of upgrades.

Yes and no. For instance, they still haven't received the upgrades that would allow them to operate properly up around the Arctic despite the R&D being successfully completed ages ago. And even before the upgrades, implemented or otherwise, their unit price was already exceeding that of the (by then truncated in numbers) Seawolf class (and the third boat was being effectively converted into a sub-class for special operations support with all the additional costs that implies but the Virginia class was still costing more than the Seawolfs).

 

[Yellow Palace]

Plus inflation is a bitch.

Inflation accounts for a hell of a lot. And making like-for-like comparisons of defence equipment procurement (or operating) costs is damn near impossible from outside. It's hard enough from the inside.

 

[Scott Kenny]

Yes and no. For instance, they still haven't received the upgrades that would allow them to operate properly up around the Arctic despite the R&D being successfully completed ages ago. And even before the upgrades, implemented or otherwise, their unit price was already exceeding that of the (by then truncated in numbers) Seawolf class (and the third boat was being effectively converted into a sub-class for special operations support with all the additional costs that implies but the Virginia class was still costing more than the Seawolfs).

What unit price are you using?

All the R&D should be stuck on Seawolf, and the plug R&D should be attached to Jimmy Carter. So you should be trying to compare Virginia class costs to that of Connecticut.

 

[Sbiper]

In relation to the discussions in the USN about the move from 700ft to 1300ft (Scorpion to Thresher) the USN and its designers seemed to have not fully appreciated the dangers involved. The Threshers retained significant lengths of unneeded ambient seawater pressure piping within their hulls (heads for example) so as is often the case designs 'fail' at their margins - the hull of USS Thresher collapsed at about 1900 feet, a testament to its over all soundness BUT - some of the details in its design were inherently poor for her designed diving depth.

While I'm sure we would all delight if SSN's had the performance of the ceramic hulled USS Challenger in Joe Buff's novels, in the real world the technology associated with making such deep diving SSN's is probably not there AND equally important there is no overriding tactical reason for submarines to go that deep, never mind the likely horrendous expense of such a deep diving depth.

A poster above mentioned that the jump from 700ft to 1300ft was made relatively quickly and in the spirt of the late 50's - early 60's it was probably assumed that similar jumps to deeper diving depths would come just as quickly and easily.