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

Sferrin said:
Here's actual hardware. You can see the spot for the planes on the sail. Nothing on hull.

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I see, you were talking about the Columbia. I was confused because of the thread topic.

I don't think a lack of under-ice capability has any impact on the vulnerability of SSBNs. The Pacific and Atlantic are big and modern submarines are very quiet. Fairwater planes are simpler and easier to maintain (I have heard the retractable bow planes require a lot of maintenance). The only point to having bow and fairwater planes is control at periscope depth, and because fairwater planes are closer to the center of buoyancy, they offer superior depth control, although the Columbia's sail is so far forward I doubt it makes much of a difference. The Ohio's fairwater planes apparently worked just fine, so why change?

Keep in mind also that it is not sufficient just to have the sail poke through the ice like on an SSN. To launch missiles, the deck must be pushed far enough out of the ice that opening the missile hatches is sufficient to clear the ice. The Russian SSBNs capable of under-ice operation have very large reserve buoyancies which allows them to do this. The Ohio has a reserve buoyancy of ~10%, and the Columbia will likely be similar. For comparison, the Russian Delta IV has a reserve buoyancy of ~25% and the Typhoon ~50%.
 
Can US SSBNs even launch missiles while surfaced? The one time they tried that with a Polaris submarine it welded all the other hatch covers shut.
 
Not James Stockdale said:
Can US SSBNs even launch missiles while surfaced? The one time they tried that with a Polaris submarine it welded all the other hatch covers shut.
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Yes, and the whole welding idea is an old sea story. The missile's first stage ignites when it is ~40 feet in the air, so the actual heating experienced by the deck is minimal. Besides, the actual tube muzzle hatch is beneath the deck, so the exhaust would have to flow through the gap between the fairing over the tube and the deck to reach the muzzle or seal that gap, neither of which is plausible.
 
Given the range of Trident II, especially with the lighter payloads they carry, and the typical patrol areas well south of the Arctic, I suspect the "surfacing through ice to launch missiles" scenario would apply more to SSNs than SSBNs. The Russian SSBNs spend much more of their time deep in the Arctic, so it's a much more immediate concern for them. The problem with designing a US submarine to do that is that the only time it would really be applicable is if you wanted to shoot Tomahawks or CPS at Russian air defense sites along the northern coast if Siberia. Just about anything else in range can be reached without going under the ice. Given the fact that China is the Main Enemy right now, I doubt there is much desire to incur the costs of bow-mounted planes when they are not very likely to be of much use.

Maybe there are other ways of solving the communications issue, like upward-firing rockets or USVs that could punch through the ice and send up an antenna.
 
Sferrin said:
I'm thinking we may see a day where under the ice is the ONLY safe place for SSBNs. Moving the planes back to the sail seems short-sighted. Did they state why they changed their mind?
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Columbia-class was designed when the expectation was that the Arctic was going to be ice-free for most of their service.

In addition, remember that you'd have to get the entire missile deck through the ice, not just the sail, if you want to launch missiles.



Not James Stockdale said:
Given the range of Trident II, especially with the lighter payloads they carry, and the typical patrol areas well south of the Arctic, I suspect the "surfacing through ice to launch missiles" scenario would apply more to SSNs than SSBNs. The Russian SSBNs spend much more of their time deep in the Arctic, so it's a much more immediate concern for them. The problem with designing a US submarine to do that is that the only time it would really be applicable is if you wanted to shoot Tomahawks or CPS at Russian air defense sites along the northern coast if Siberia. Just about anything else in range can be reached without going under the ice. Given the fact that China is the Main Enemy right now, I doubt there is much desire to incur the costs of bow-mounted planes when they are not very likely to be of much use.
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Remember that CPS is very close to Polaris range.



Not James Stockdale said:
Maybe there are other ways of solving the communications issue, like upward-firing rockets or USVs that could punch through the ice and send up an antenna.
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Well, the Virginias are still pretty good for under ice, and we won't have SSNX till the 2040s.
 
Scott Kenny said:
Columbia-class was designed when the expectation was that the Arctic was going to be ice-free for most of their service.
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I'm almost certain this is not true, for a few reasons. Even under high emissions scenarios, the Arctic will not be ice-free in winter. When climate scientists talk about an "ice-free" Arctic, they are usually referring to the summer sea ice extent.

Even if we warmed the planet to eliminate sea ice in the Arctic (in which case we'd have bigger issues), I don't see why U.S. SSBNs would switch from their (ice-free) patrol areas in the North Atlantic and North Pacific to an ice-free Arctic. The whole point of using the Arctic as an SSBN patrol area, as the Soviets/Russians do, is that the sea ice can present challenging sonar conditions that make ASW difficult, and of course it is conveniently close for them.
 
Scott Kenny said:
Columbia-class was designed when the expectation was that the Arctic was going to be ice-free for most of their service.
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Just curious, but are you implying that that expectation has changed? Unless I'm mistaken, the only change in expectation from scientists with regards to sea-ice in the arctic is that its going to be gone sooner than what was thought when the Columbia class was being designed. So the design choice of sail mounted planes is arguably even more valid now (I remember reading that sail mounted planes are quieter in use as well)
 
SCAT-15F said:
Just curious, but are you implying that that expectation has changed? Unless I'm mistaken, the only change in expectation from scientists with regards to sea-ice in the arctic is that its going to be gone sooner than what was thought when the Columbia class was being designed. So the design choice of sail mounted planes is arguably even more valid now (I remember reading that sail mounted planes are quieter in use as well)
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No, in the early 00s it was expected that the arctic would be ice free by now. At least in the publications I was reading.
 
SCAT-15F said:
Just curious, but are you implying that that expectation has changed? Unless I'm mistaken, the only change in expectation from scientists with regards to sea-ice in the arctic is that its going to be gone sooner than what was thought when the Columbia class was being designed. So the design choice of sail mounted planes is arguably even more valid now (I remember reading that sail mounted planes are quieter in use as well)
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I was taught in high school (late 2000s) that the Arctic would be ice free by 2020.
 
If the AMOC shuts down we'll definitely have more ice in certain areas, but NASA/NOAA predictions over the past 25 years have underestimated the rate of arctic sea ice loss. Warming in the polar regions has been disproportionately greater than the rest of the planet.
 
I have heard that late summer loss has slowed since '05 but the overall rate of loss is still higher than pre-'05 predictions. I would of course prefer more ice rather than less. Good for subs and the planet.
 
SSNX is sounding more and more like a missed opportunity. Nothing more than continued evolution of the same US design philosophy since the Skipjack: 90% emphasis on the front end of the boat and 10% on the back. A couple submariners turned engineers back in 1990 came up with a Seawolf follow-on design that was light years ahead of what SSNX is shaping up to be. It was published in proceedings. The 1990's shift to a brown-water force killed that. Even if SSNX manages to match Seawolf performance-wise, Seawolf itself had its specs reduced from the start with the dropping of HY-130. NG's NNEMO-1 advanced hull form project back in 2003 showed some divergent thinking, as did the French SMX-31 and BAE designs. Hopefully we get something along those lines.
 
SCAT-15F said:
A couple submariners turned engineers back in 1990 came up with a Seawolf follow-on design that was light years ahead of what SSNX is shaping up to be.
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This the 'wish list' boat from LCDR Pepper with fusion reactors and capable of 155 knots? Because I can make stuff up too.

SEAWOLF has a big bomb shop and a lot of performance. But VIRGINIA is a better submarine overall, and doesn't give up so much performance as is often implied.

Also remember that the purpose of the back half of the boat is to get the front half in the right place to do its job. That doesn't require depths of many thousands of feet or vast speeds.
SCAT-15F said:
NG's NNEMO-1 advanced hull form project back in 2003 showed some divergent thinking, as did the French SMX-31 and BAE designs. Hopefully we get something along those lines.
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You do realise those hull forms were designed primarily for littoral operations, the very environment you've criticised the VIRGINIA for being designed to operate in?
 
SCAT-15F said:
SSNX is sounding more and more like a missed opportunity. Nothing more than continued evolution of the same US design philosophy since the Skipjack: 90% emphasis on the front end of the boat and 10% on the back.
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The navy is still figuring out what exactly they want from SSN(X) but go off queen, apparently you're prescient
 
NMaude said:
Why is it unweldable?
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IIRC it needs to be preheated to something like 200 celcius otherwise you get cracking, and even then the weld temperature must be closely monitored. Technically not impossible to do, but with larger pieces like pressure hull it's functionally impossible.
 
Finding a fill material that performs across the range of an SSN's operating environment is also a challenge. IIRC, one test from the 90s was progressing well until it became clear the long-term ductility of the weld was something like half that of the steel.

With modern advanced in welding, better tools to monitor weld quality, etc it's probably doable. But the cost would be considerable. Much like when people have proposed moving off HY steel to an entirely new alloy the question becomes, is the potential extra performance over HY-100 worth it?
 
Moose said:
Finding a fill material that performs across the range of an SSN's operating environment is also a challenge. IIRC, one test from the 90s was progressing well until it became clear the long-term ductility of the weld was something like half that of the steel.

With modern advanced in welding, better tools to monitor weld quality, etc it's probably doable. But the cost would be considerable. Much like when people have proposed moving off HY steel to an entirely new alloy the question becomes, is the potential extra performance over HY-100 worth it?
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Basically the same thing why people aren't building more subs out of titanium alloy. We can DO it, but the costs outweigh the benefits.
 
Moose said:
Finding a fill material that performs across the range of an SSN's operating environment is also a challenge. IIRC, one test from the 90s was progressing well until it became clear the long-term ductility of the weld was something like half that of the steel.

With modern advanced in welding, better tools to monitor weld quality, etc it's probably doable. But the cost would be considerable. Much like when people have proposed moving off HY steel to an entirely new alloy the question becomes, is the potential extra performance over HY-100 worth it?
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Maybe you could do some friction stir welding? But I kinda assume you have to basically re-heat treat the steel after that, given you're melting it. Or something else nonsensical.
 
Yellow Palace said:
This the 'wish list' boat from LCDR Pepper with fusion reactors and capable of 155 knots? Because I can make stuff up too.

SEAWOLF has a big bomb shop and a lot of performance. But VIRGINIA is a better submarine overall, and doesn't give up so much performance as is often implied.

Also remember that the purpose of the back half of the boat is to get the front half in the right place to do its job. That doesn't require depths of many thousands of feet or vast speeds.

You do realise those hull forms were designed primarily for littoral operations, the very environment you've criticised the VIRGINIA for being designed to operate in?
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Ha ha. No, it's not the Pepper "wish list" boat. It was a something doable with 1990's technology. 40+ knots, spherical pressure hulls, 4000 ft test depth, distributed weapons, retractable sail. Yes, NNemo is littoral focused, but its still double hulled, and the BAE and French designs aren't specifically for littorals.
 
Felocie said:
The navy is still figuring out what exactly they want from SSN(X) but go off queen, apparently you're prescient
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Hmmm, I must have hit a nerve. The Navy's been refining the requirements for years. They're not just starting now and they're not going to do a 180 from their entrenched design philosophy.
 
whatismoo said:
Maybe you could do some friction stir welding? But I kinda assume you have to basically re-heat treat the steel after that, given you're melting it. Or something else nonsensical.
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The trick is that apparently Friction Stir Welding does NOT heat the metal over it's melting point, "only" to the point of softening. But I don't know how well it works on really thick slabs of steel.
 
SCAT-15F said:
Ha ha. No, it's not the Pepper "wish list" boat. It was a something doable with 1990's technology. 40+ knots, spherical pressure hulls, 4000 ft test depth, distributed weapons, retractable sail. Yes, NNemo is littoral focused, but its still double hulled, and the BAE and French designs aren't specifically for littorals.
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Well, don't be shy, show us the money the design then.
 
MihoshiK said:
IIRC it needs to be preheated to something like 200 celcius otherwise you get cracking, and even then the weld temperature must be closely monitored. Technically not impossible to do, but with larger pieces like pressure hull it's functionally impossible.
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It was originally supposed to be HY-150, but getting it to weld at all reduced the strength.
MihoshiK said:
Well, don't be shy, show us the money the design then.
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FWIW I had a look but USNI either hasn't digitised the article or hasn't indexed it for search.
 
SCAT-15F said:
Hmmm, I must have hit a nerve. The Navy's been refining the requirements for years. They're not just starting now and they're not going to do a 180 from their entrenched design philosophy.
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You haven't hit a nerve, you just didn't say anything of substance. Their design philosophy has/is consistently producing amongst the most lethal boats on the planet and SSN(X) shows no signs of changing this fact
 
Yellow Palace said:
It was originally supposed to be HY-150, but getting it to weld at all reduced the strength.

FWIW I had a look but USNI either hasn't digitised the article or hasn't indexed it for search.
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That's fine, let @SCAT-15F have a go at it, he was so sure it exists, he should have no trouble finding it.
 

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