Trident C4 and GLCM for the UK

[Yellow Palace]

I've taken this to the AH forum as it's veering into pure speculation.

Wait a minute.....is there a viable AH scenario in here?
That if Polaris had not been deferred, the GLCM (wasn't it supposed to be tri-service?) could have proceeded?

Flipside is maybe there was a tactical need for a different warhead than those the US had pledged to SACEUR and the UK was examining development of such?
Question is what might that be?

Rumour is enhanced radiation work a.k.a neutron bomb type concepts.

I suspect this hands the reins to the disarmament lobby. I'd need to go back to the sources (Duff-Mason for Trident C4, somewhere in the Thatcher archives for GLCM), but what it probably looks like is:

• Trident submarines are ordered and delivered 5-6 years earlier, and Polaris retired that much earlier. There may be a 5th boat ordered, but it is probably cancelled when the Cold War ends.
• GLCM, delayed until after Trident, is cancelled as a result of either the IMF treaty or the end of the Cold War.
• The UK's nuclear weapons infrastructure suffers worse skill fade than in OTL, given earlier Holbrook/W76 completion and the cancellation of both GLCM and TASM.
• When the US retires Trident C4 in 2005, the UK is left holding the bag with an end-of-life missile system and submarines approaching the need for replacement.
• The 2008 financial crisis, plus the political environment (domestic and international) of the mid-2000s, the decline of UK nuclear industry, and the need to find two land wars on a peacetime budget makes 'retire without replacement' look like a very attractive option.

 

[Scott Kenny]

No, I don't think that Trident 1 is a viable thing in any timeline.

The increased diameter of Trident 2 was pretty well known early on. The UK politicians would be ... even dumber than we usually mock them for being if they didn't at least buy their subs with the tubes for Trident 2. Even if, like the first half of the Ohio-class, they started life with Trident 1s.

 

[zen]

When would we know what diameter Trident 2 was fixed in design?
March 14, 1974
so AI tells me
So.....by the time WE.177 replacement studies, and by the time of what became the Vanguard SSBN, Trident II diameter was fixed.

Meaning the transition from Trident I to Trident II isn't impossible and would be part of upgrade process in the 90's to early 2000's.

 

[Scott Kenny]

When would we know what diameter Trident 2 was fixed in design?
March 14, 1974
so AI tells me
So.....by the time WE.177 replacement studies, and by the time of what became the Vanguard SSBN, Trident II diameter was fixed.

Meaning the transition from Trident I to Trident II isn't impossible and would be part of upgrade process in the 90's to early 2000's.

Isn't impossible but also isn't exactly easy. The tube liners were grouted/concreted into place on the Ohios, which took some serious work to remove. 19ish months in the drydocks (based on USS Alaska), if not more. USS Henry M Jackson spent 4 years in shipyard for her combined refueling and D5 backfit. With only 4 boats, can the RN afford to have one out of service for ~2 years?

IMO you'd be a lot better served building straight with Trident 2, even as the "first adopter". That said, Trident 2 first flight was 1989.

 

[Yellow Palace]

Please do read Duff-Mason. The argument was hashed out in detail in 1978.

Broadly: five boats with C4 was the cheapest way to meet the UK requirement. D5 was more expensive and the additional capability wasn't required for the UK requirement. On the submarine side, using the 'latest Poseidon submarine' missile compartment would be smaller and cheaper, but the Ohio section would provide the flexibility stated. About a year of further studies would be needed to make a decision - but in either case C4 was the initially envisaged missile.

What tipped it wasn't the all-D5 force, but the fact that D5 could carry more warheads, allowing one boat on station to cover the targets. That in turn meant delaying the programme until D5 was available. If you want to avoid the delay, in order to bring forward the TNF replacements, you have to go with C4.

 

[Scott Kenny]

Please do read Duff-Mason. The argument was hashed out in detail in 1978.

I'll add it to the list.

Broadly: five boats with C4 was the cheapest way to meet the UK requirement. D5 was more expensive and the additional capability wasn't required for the UK requirement. On the submarine side, using the 'latest Poseidon submarine' missile compartment would be smaller and cheaper, but the Ohio section would provide the flexibility stated. About a year of further studies would be needed to make a decision - but in either case C4 was the initially envisaged missile.

What tipped it wasn't the all-D5 force, but the fact that D5 could carry more warheads, allowing one boat on station to cover the targets. That in turn meant delaying the programme until D5 was available. If you want to avoid the delay, in order to bring forward the TNF replacements, you have to go with C4.

Yeah, I'm seeing that.

The pain is that the D5 Backfit takes a big chunk of time, which would probably force a 6th boat to be built to cover for when it was time to do those refits. Or other nasty schedule-related shenanigans that would absolutely suck for the crews.

 

[zen]

Isn't impossible but also isn't exactly easy. The tube liners were grouted/concreted into place on the Ohios, which took some serious work to remove.

So we assume the RN SSBN fleet will use exactly the same tubes as the USN?
But.....if the RN knows Trident II is coming and of greater diameter. Would they commit to such, knowingthe potential cost/time issues to transition to Trident II?

Edited in more thinking...

If we start with Trident C4 at 8 RVs per missile and 16 missiles per boat of 5 boats.
Assuming 3 must be loaded produces a maximum of 384 warheads.
We know WE.177 successor was expected to be 230 warheads followed by at least 40 nuclear depth charges and possibly nuclear warheads for a Torpedo of limited numbers.
This implies a nuclear arsenal of over 654 warheads for various levels of sustainment.

This represents a substantial increase over Polaris and WE.177. Though domesticates potential Lance successor?

 

[Scott Kenny]

So we assume the RN SSBN fleet will use exactly the same tubes as the USN?
But.....if the RN knows Trident II is coming and of greater diameter. Would they commit to such, knowingthe potential cost/time issues to transition to Trident II?

Because Trident 1 was going to be spun down eventually, which leaves the UK stuck holding Trident 1s in the 2000s if you don't build 83" tubes.

So the big tubes with a liner for Trident 1/Poseidon sized missiles is a really strong discussion, despite how sucky it is to remove the liners later on.

If we start with Trident C4 at 8 RVs per missile and 16 missiles per boat of 5 boats.
Assuming 3 must be loaded produces a maximum of 384 warheads.
We know WE.177 successor was expected to be 230 warheads followed by at least 40 nuclear depth charges and possibly nuclear warheads for a Torpedo of limited numbers.
This implies a nuclear arsenal of over 654 warheads for various levels of sustainment.

This represents a substantial increase over Polaris and WE.177. Though domesticates potential Lance successor?

I mean, just the fact of the newer bigger missile would mean a significant warhead increase. Whether the UK went to Poseidon, Trident 1, or direct to Trident 2.

 

[zen]

What if the UK developed a removable liner for the silos?

 

[Scott Kenny]

What if the UK developed a removable liner for the silos?

I mean, the US tube liners were removable, it just took a lot of work (~18 months). I'm not sure that it'd be viable to not have glued-in liners.

 

[zen]

Depends on specifics of the silo. This may mean there's scope for a domestic silo design. Maybe even one that sways the USN?

 

[Yellow Palace]

If we start with Trident C4 at 8 RVs per missile and 16 missiles per boat of 5 boats.
Assuming 3 must be loaded produces a maximum of 384 warheads.

Stated requirement for C4 was 576 warheads, which equates to 4.5 boats.

Because Trident 1 was going to be spun down eventually, which leaves the UK stuck holding Trident 1s in the 2000s if you don't build 83" tubes.

There were at least some voices arguing that by then the UK would have sufficient experience with C4 that it wouldn't be a problem to maintain them independently. This is before the joint stock at King's Bay was agreed.

At the same time, if C4 is chosen because it's cheaper than D5, Treasury is not going to be impressed by an argument to build unnecessarily large submarines to take a missile that's been deemed too big and expensive.

Would it be a mistake to stick with C4, and especially to build a submarine that can't be upgraded to D5 later? Absolutely. But it's the kind of mistake I can see the UK making.

 

[Scott Kenny]

There were at least some voices arguing that by then the UK would have sufficient experience with C4 that it wouldn't be a problem to maintain them independently. This is before the joint stock at King's Bay was agreed.

You'd still need a factory to make new rocket motors. Or buy them from the US, but that gets expensive and costs dollars instead of pounds. Plus decommissioning those old rockets is ... exciting. "making big holes in the desert" exciting.

At the same time, if C4 is chosen because it's cheaper than D5, Treasury is not going to be impressed by an argument to build unnecessarily large submarines to take a missile that's been deemed too big and expensive.

Would it be a mistake to stick with C4, and especially to build a submarine that can't be upgraded to D5 later? Absolutely. But it's the kind of mistake I can see the UK making.

So the C4-Vanguards would be the size of a Benjamin Franklin class boat? ~8250 tons submerged? Or maybe a little shorter and lighter if they only go for 12 tubes instead of 16.

 

[Yellow Palace]

So the C4-Vanguards would be the size of a Benjamin Franklin class boat? ~8250 tons submerged? Or maybe a little shorter and lighter if they only go for 12 tubes instead of 16.

Unclear, it doesn't seem that a decision was made by the time D5 was selected. Options were for the missile compartment to be based on 'the latest Poseidon submarine' or 'Ohio class'. The latter gets you a D5 compatible boat, of course. But if the incentive is a cheaper submarine and missile, I could see the former being preferred.

 

[zen]

The last thing the Treasury wants to hear is you need a new submarines because of a missile diameter change.
They would see adaptable SSBNs as cheaper over the long run.