Successor/Dreadnought Class SSBN

One problem that will have to be urgently addressed is that parts of the design are arguably rather badly out of date, only 12 SLBM tubes for example.
 
If only 12 SLBM, the question to asked is concerning the performance of the Bus and individual RVs.

If the RVs be MARVs then their cross range 'footprint' is greater. Increasing the dispersion of targets a single Bus can engage.

If the RVs be smaller and lighter, then the quantity deployed per Bus can increase for a given 'throw' distance.

If the Bus carries more maneuvering fuel, it can increase the spread pattern of bombardment.

Lots of things to contemplate here.
 
Grey Havoc said:
One problem that will have to be urgently addressed is that parts of the design are arguably rather badly out of date, only 12 SLBM tubes for example.
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While four or five boats with sixteen tubes, fully bombed up, is an appealing thought - it's worth remembering that the current UK bombers sail with only eight missiles with less than half their maximum payload.
Forest Green said:
Solve problem with a 5th sub.
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Probably cheaper than scrambling to add another four tubes into a boat under construction. Finding the missiles and warheads to upload even a 4x12 fleet would probably pose challenges, though. The defence nuclear enterprise hasn't operated at that scale in a generation for missiles, and never for warheads.
 
Yellow Palace said:
While four or five boats with sixteen tubes, fully bombed up, is an appealing thought - it's worth remembering that the current UK bombers sail with only eight missiles with less than half their maximum payload.

Probably cheaper than scrambling to add another four tubes into a boat under construction. Finding the missiles and warheads to upload even a 4x12 fleet would probably pose challenges, though. The defence nuclear enterprise hasn't operated at that scale in a generation for missiles, and never for warheads.
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thebulletin.org

United Kingdom nuclear weapons, 2024

For decades, the United Kingdom has maintained a stockpile of approximately 225 nuclear warheads—up to 120 of which are available for delivery by four Vanguard-class nuclear-powered ballistic missile submarines. This stockpile is now increasing.
thebulletin.org thebulletin.org
 
zen said:
Do they?
I thought one had a single RV....
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Generally understood to be 40 warheads on 8 missiles - though how those are distributed isn't public knowledge, of course.

AIUI, the increase in permitted warheads is to allow manufacturing of new ones to replace HOLBROOK, not to increase the number deployment.
Scott Kenny said:
Can't refit a sub to have more tubes, that's something you need to do at the design step.
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Technically you can cut the hull and insert a plug with additional tubes. You shouldn't, especially if the line is still hot for additional boats. Plays havoc with ballast & trim calculations. But you could, if you really wanted to.
 
Yellow Palace said:
AIUI, the increase in permitted warheads is to allow manufacturing of new ones to replace HOLBROOK, not to increase the number deployment.
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Astrea/mk4 is the next generation.

Nothing to say we cannot expand numbers....
 
Scott Kenny said:
Can't refit a sub to have more tubes, that's something you need to do at the design step.
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????

"George Washington was originally laid down as the attack submarine USS Scorpion (SSN-589). During construction, she was lengthened by the insertion of a 130 ft (40 m)-long ballistic missile section and renamed George Washington; another submarine under construction at the time received the original name and hull number." Wikipedia
 
Yellow Palace said:
Technically you can cut the hull and insert a plug with additional tubes. You shouldn't, especially if the line is still hot for additional boats. Plays havoc with ballast & trim calculations. But you could, if you really wanted to.
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Absolutely shreds your reserve buoyancy levels.

aim9xray said:
????

"George Washington was originally laid down as the attack submarine USS Scorpion (SSN-589). During construction, she was lengthened by the insertion of a 130 ft (40 m)-long ballistic missile section and renamed George Washington; another submarine under construction at the time received the original name and hull number." Wikipedia
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That can possibly work if the fast attack design has lots of reserve buoyancy and the missile compartment is neutrally buoyant. The question is then "neutrally buoyant at what waterline?"

If the missile compartment is neutrally buoyant at depth, then it will greatly reduce your reserve buoyancy on the surface.
If the missile compartment is neutrally buoyant at the surface, you'll need larger ballast tanks to be able to dive.
 
Which tradeoff (or mix) was selected for the GW class, and how did that work out operationally?
 
aim9xray said:
????

"George Washington was originally laid down as the attack submarine USS Scorpion (SSN-589). During construction, she was lengthened by the insertion of a 130 ft (40 m)-long ballistic missile section and renamed George Washington; another submarine under construction at the time received the original name and hull number." Wikipedia
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Wikipedia is not quite wrong, but a bit misleading. When the original Scorpion was re-ordered as an SSBN, she was essentially just a pile of steel. I'm not sure any hull cylinders were welded up when the re-ordering decision was made. So the cutting was done on paper instead of literally at the shipyard. It probably would have been possible to take a completed SSN and convert her into an SSBN, but that would have been much harder.

The addition of the missile compartment ended up requiring large internal main ballast tanks to be added to the Skipjack design. It worked out in the end but the solution was not really optimal.
 
The Dreadnought & Columbia SSBN classes do not have a single missile compartment.

The common missile compartments for the Dreadnought and Columbia classes are designed in 4 tube units. 3 units in a Dreadnought and 4 in a Columbia. So, in theory just add another unit.

"In a sensible move to reduce duplication of effort, the Dreadnought class share a common missile compartment design with the US Navy’s Columbia class SSBNs. Babcock in Rosyth and Bristol are involved in the manufacture of the Missile Tube Assemblies (MTAs) and since 2014, has won contracts for 57 MTAs. Another contract was secured in June 2020 for an additional 18, will bring the total made by Babcock to 75. The quad-pack of 4 tubes is about 80% fitted out with wiring and pipework before insertion into the pressure hull. Each Dreadnought boat will be fitted with 3 quad packs, giving 12 tubes while the USN Columbias will have 16 tubes."

"The first 4 missile tubes were delivered to Barrow in April 2020 and welding into a Quad Pack is complete. Integration into a pressure hull section progressed well. A further two tubes were delivered in July 2020."

www.navylookout.com

Progress on the Royal Navy’s Dreadnought class submarine programme | Navy Lookout

www.navylookout.com www.navylookout.com

So that leaves the question of buoyancy to be resolved.
 
aim9xray said:
Which tradeoff (or mix) was selected for the GW class, and how did that work out operationally?
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Combined response:
Vepr157 said:
The addition of the missile compartment ended up requiring large internal main ballast tanks to be added to the Skipjack design. It worked out in the end but the solution was not really optimal.
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Looks like the answer for the "emergency" SSBNs was "Missile Compartment neutrally buoyant at surface, add bigass ballast tanks."


Vepr157 said:
Wikipedia is not quite wrong, but a bit misleading. When the original Scorpion was re-ordered as an SSBN, she was essentially just a pile of steel. I'm not sure any hull cylinders were welded up when the re-ordering decision was made. So the cutting was done on paper instead of literally at the shipyard. It probably would have been possible to take a completed SSN and convert her into an SSBN, but that would have been much harder.
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As I understand it, the keel had been laid and needed to be cut to install the missile compartment.

But it was very early in the build that the original Scorpion was re-ordered. They didn't literally cut the boat in half and install a plug like they did for Parche (after several years in service) or Jimmy Carter (during construction).


EwenS said:
The Dreadnought & Columbia SSBN classes do not have a single missile compartment.
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You're misunderstanding. The quads get put into a hull cylinder and then the cylinder is welded into a complete missile compartment. The whole thing including the hovering and missile compensation tanks on the ends are part of the missile compartment.

There's not a block of 4 tubes that are enclosed in watertight bulkheads, and then 3 or 4 of those stacked together.

Bulkheads are noise sources!!! (well, the watertight doors in the bulkheads are noise sources)


EwenS said:
The common missile compartments for the Dreadnought and Columbia classes are designed in 4 tube units. 3 units in a Dreadnought and 4 in a Columbia. So, in theory just add another unit.

[...]

So that leaves the question of buoyancy to be resolved.
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Which is going to be difficult, since the Dreadnought already has a partial double hull for smaller ends. Hard to add more/larger ballast tanks.



zen said:
Also resolves that the missile tubes seem to be being built in the UK. So how many have shipped to the US?
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At least 16, probably more like 32.
 
75 missile tube assemblies contracted, but Dreadnought class only need 48....so 27 excess. Presumably for USN.

However it's not certain that of the then contract, how many would be needed for Dreadnoughts or how many more might be contracted in future for the USN.

All depends on schedules.
 
zen said:
75 missile tube assemblies contracted, but Dreadnought class only need 48....so 27 excess. Presumably for USN.

However it's not certain that of the then contract, how many would be needed for Dreadnoughts or how many more might be contracted in future for the USN.

All depends on schedules.
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Just like they make extra missiles for spares and testing, it's probably the same with tubes.
 
Well....maybe.....maybe not.

But 27 leaves would allow 2 more Dreadnought SSBN for a total of 6...

or ...

Considering these might be used in SSN-AUKUS (SSN-R) which looks like only 4 tubes in the design recently shown (spread alone the center line, 1 for'd of the Fin, 3 aft) and can accommodate a number of VL Tomahawk type weapons per tube......would allow for 6 such submarines.
 
Scott Kenny said:
As I understand it, the keel had been laid and needed to be cut to install the missile compartment.
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Like I said, she was basically just a pile of steel when the decision to reorder happened. The term "keel-laying" for modern submarines is essentially ceremonial in that there is no actual keel to speak of. The original Scorpion was laid down on 1 November 1957 and she was reordered as an SSGN(FBM) on 31 December 1957. To give you an idea of the pace of construction, this is a photo of the Scamp about six months after she was laid down:


Unless a hull cylinder was already constructed between frames 37 and 42, there will have been no cutting.
 

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TinWing said:
The shorter, single file tubes in the modified Virginia class minimize any potential arms control or proliferation controversy. Exporting a dual use SSBN/SSGN is a potential proliferation issue. Keep in mind that the Virginia class tubes are the correct diameter but are too short for Trident. Arms control seems dormant at the moment but is bound to resurface before the AUKUS class hits the water. Basically, all of the nuclear powers are facing debt crisies of varying severity, hence the inevitable return of nuclear arms control.
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On the other hand, strategic Arms Control considerations are pretty much on the road to extinction.
 
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The massive cuts in conventional military forces since 1945, not only reflect a period of relative peace.

But the period where escalation to nuclear weapons use obviates their (massive armies) utility is the same.
It was cheaper to threaten the use of nukes than raise massive armies.

The Ukraine invasion is a return of old pre-nuclear warfare in scale.
 
Vepr157 said:
Like I said, she was basically just a pile of steel when the decision to reorder happened. The term "keel-laying" for modern submarines is essentially ceremonial in that there is no actual keel to speak of. The original Scorpion was laid down on 1 November 1957 and she was reordered as an SSGN(FBM) on 31 December 1957. To give you an idea of the pace of construction, this is a photo of the Scamp about six months after she was laid down:


Unless a hull cylinder was already constructed between frames 37 and 42, there will have been no cutting.
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That link is dead - Navsource has moved their site to a .net address instead of the old .org address.

http://www.navsource.net/archives/08/08588.htm
 
I've heard the words 'turbo-electric drive' and 'shaftless drive' thrown around in relation to both the Columbia-class SSBNs and these Dreadnought-class SSBNs - what is this, why is it useful, and will it be equipped to these boats?
 
It's essentially the submarine-equivalent to a surface ship Azipod, i.e. the electrified nature of the drive train is taken advantage of to locate the motor directly at the propeller, instead of amidships with a long shaft in between. Power is instead transmitted by cable from the prime mover and generator (which are probably still going to be where they always used to be, due to stability and balance). This naturally eliminates any drawbacks caused by the presence of a shaft, such as maintenance, packaging of other equipment, damage control etc.. It opens up a few additional degrees of design freedom.
 
Reuben James said:
I've heard the words 'turbo-electric drive' and 'shaftless drive' thrown around in relation to both the Columbia-class SSBNs and these Dreadnought-class SSBNs - what is this, why is it useful, and will it be equipped to these boats?
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Turbo-electric drive: Electric motor drives the screw directly, no reduction gears on the shaft.
Shaftless drive: Electric motor driving the screw is relocated outside the pressure hull. (Shaftless is a subset of turbo-electric drive)

In both cases the ships just have big electrical generators powered by steam turbines. Actually, probably 2 big generators and 2 small generators.

The primary advantage is that the reduction gears are the primary noise source for submarines, as they're connected directly to the shaft and screw outside the hull.

A secondary advantage is that you can use smaller steam turbines for the generators than you need for the main engines.

Disadvantage is that the generators plus steam turbines are bigger than just the main engines. Note that the Columbia class is just as long as the Ohios, despite not having anywhere near as many tubes. Roughly speaking, the Columbia class missile compartment is 50ft shorter than an Ohio-class, while the engineroom is 50ft longer.
 
Regarding turboelectric drive, there is a fantastic declassified 1963 study by Electric Boat on various possible propulsion machinery and propulsor arrangements. Of course much of the specific discussion on turboelectric drive is outdated with the advent of solid-state power conversion in recent decades, but it is still a highly informative document on the challenges faced when designing a quiet submarine.
 

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