PC/WI "POSEIDON" armed SSBN's for the RN

WILDGEESE

Gone Fishin'
With a pod after 1970, what events would it take for the UK gov't to put a minimal fleet of 4 Poseidon armed SSBN's into service for the Royal Navy either as a replacement of the "R" boats or an expansion of the deterrent force?

Bonus points if you can also give a name to the class (my own eg "Endeavour" class) or give a rough outline of the SSBN class itself, for example I'm thinking of a class of sub's based on a lengthened "Swiftsure" class.

Would this be possible?

Regards filers
 
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Very possible - in fact it almost happened:
wiki said:
Something had to be done in order to maintain the relevance of the UK's nuclear deterrent. Although developments in the ABM field had been watched throughout the 1960s, exactly what to do about the problem apparently remained a fairly low priority. In 1967 the US offered a newer version of the Polaris, the A3T design, which featured a "hardened" missile airframe intended to better protect it against ABMs. As the UK had not yet received their missiles, they agreed to use the A3T version as it required relatively few other changes.[citation needed]

In 1970 serious efforts to explore the ABM problem started. By this point the US and USSR had agreed in the ABM Treaty to deploy up to 100 ABMs at only two sites. MIRVs had so seriously upset the balance between ABM and ICBM that both parties agreed to limit ABM deployment largely as a way of avoiding a massive buildup of new ICBMs. The only good news for the UK in this development was that it clearly defined the problem they were facing; their attacks had to be able to credibly defeat a 100-interceptor ABM defense around Moscow. Thus started project KH.793, a one-year project to identify potential solutions.

One option would be to build additional Polaris platforms and keep more of them at sea. Two Resolutions would throw 96 warheads and almost guarantee penetration, while three would make it a certainty. This would require a fleet of at least five submarines to keep two on station at all times, as well as larger crew complements, training and logistics support, and appeared to be the most expensive option.

Several "low cost" options were also explored. Among these were "Topsy", the A3T missile the UK had already agreed to use. Another option was Antelope, which used hardened warheads along with penaids, although it reduced the payload to two warheads in order to save weight for the penaids. They also explored a "superhardened" version known as Super Antelope, a further improvement on the warhead that also used a manoeuvrable warhead "bus" to deploy the penaids further apart in space.

The Royal Navy preferred to upgrade to the Poseidon missile, increasing the number of warheads from three per missile to between ten and thirteen of a newer and lighter design. In this case a single Resolution could launch up to 208 warheads, guaranteeing that some would get through. This option also had the advantage of maintaining commonality with the US Navy, as well as offering greater range, and thus increasing the safety of the launch submarines.

The US also favoured the Poseidon, although for more technical reasons. They felt that while the decoy approach was useful against near-term ABMs deployed by the USSR, that it was considerably less useful against "point defence" type interceptors. This is because the decoys are so much lighter than warheads; when they started to hit the upper atmosphere the decoys would slow more than the warheads and thus "declutter", allowing the warheads to be attacked. This would require a much faster-reacting system than a long-range interceptor, one that could safely wait until only a few moments before detonation, but this was by no means impossible and was part of the US's own ABM systems.

As the UK had decided to produce its own warheads and bus, this option would require considerable development effort in order to produce a new MIRV bus of their own. Although in theory the UK might be able to use the US-designed bus, these options were being explored in the midst of the ABM Treaty, and it was not clear whether or not the treaty might forbid this technology being transferred. Some related options were explored, including "Option M" which used a simple "de-MIRVed" bus, "Hybrid" (or "Stag") which put the newer Poseidon warheads on the existing Polaris A3T missiles, and "Mini Poseidon", a similar adaptation with a smaller six-Poseidon-warhead payload on the A3T.

In the end the higher levels of the British political system decided against the urgings of their own Chiefs of Staff and went with the penaid approach on the existing A3T missile. This decision was made official late in 1973 by the Edward Heath administration, who changed the name from Super Antelope to Chevaline. The name 'Chevaline' was the result of a telephone call to London Zoo from an official at the Ministry of Defence. Prompted by a request for a name-change from his boss, the Secretary of State for Defence, Lord Carrington, the official asked the zoo to 'imagine an animal like a large antelope' and inquired whether there was such a beast. The zoo told him there was a South African creature called a Chevaline, and the official 'thought that sounded rather good'.[2] (The creature to which the zoo was probably referring was the Roan Antelope, Hippotragus equinus which is known in French as 'Antilope chevaline'.)
https://en.wikipedia.org/wiki/Chevaline
 
I did a thread a few months ago about a different chevaline, posiedon was one of the options put forward. As the discussion progressed I came to the conclusion that chevaline was a good option for whole of government reasons.
 
Does the RN even need new boats ? did the USN not rebuild its boats for the new missile ? How much work is involved and could the RN just rebuild its boats the same, I'm assuming the missile tubes are identical ?

(The real question is would this actually be cheaper than the historic choice of developing a unique none US system, ie 'Chevaline' ?)
 
I believe that the Poseidon missiles would fit into Polaris tubes readily enough by taking out the locating rings and fibreglass liners . Also Poseidon would have the handy benefit of having more range, particularly since the Chevaline had reduced range than the Polaris A3TK.

However if the British used the Poseidon they would have to design a new MIRV warhead bus from scratch. In addition, and this is probably the biggie, the British would have to design and test an entirely new warhead and then build it in great numbers. This warhead would most likely not be able to use the ET.317 warhead designed for the Skybolt and eventually used in the Polaris A3TK and virtually identical to the WE.177 aircraft bomb.
 
However if the British used the Poseidon they would have to design a new MIRV warhead bus from scratch. In addition, and this is probably the biggie, the British would have to design and test an entirely new warhead and then build it in great numbers. This warhead would most likely not be able to use the ET.317 warhead designed for the Skybolt and eventually used in the Polaris A3TK and virtually identical to the WE.177 aircraft bomb.
The resources that went into Chevaline would cover the bus quite nicely; Chevaline basically amounted to a bus for two RVs and a boatload of decoys. Designing and building a new warhead might not actually be a bad thing - AWE went through something similar in the 1970s to the Barrow shipyard in the 1990s, losing a lot of its' skilled workforce. Do Poseidon, and the workforce remains in place to support the GLCM program, Trident, and the WE.177 replacement.

With hindsight, apparently Chevaline's decoys weren't all that great and the additional warhead of standard Polaris would have been more useful. Full-dress Poseidon even better, if the US Congress would grant the export licences. The sensible thing to do would be to refit the Resolution class to carry Poseidon, so that Britain isn't a unique operator of Polaris in the 1980s. The cost savings allow you to roll out GLCM in the mid-1980s as planned, Poseidon means that the Resolution class are viable for longer so you do WE.177 replacement next, then the Vanguard class will be programmed as OTL - it was shifted to the right quite late in the program.

Incidentally, the retirement of WE.177 without replacement was largely driven by the aforementioned 'brain drain' at AWE - they didn't have the manpower to maintain it properly any more, and couldn't guarantee the safety of the weapons after about 1994. The end of the Cold War made nuclear disarmament a convenient excuse to drop the capability without awkward questions being asked. If AWE stays up to strength, that probably doesn't happen.
 
I don't think the Chevaline has a bus as such, certainly not powered like a Poseidon or Trident MIRV bus anyway. All the Chevaline bus did was tilt out the RVs and release them and then do a bit of a dance to deploy the penaids. The MIRV bus of a Posiedon did multiple rocket burn manoeuvres and at each one deployed an RV or several, this is different and more difficult/complex than the Chevaline and I think much more expensive to develop from scratch.

Why did AWRE have to support GLCM?
 
Why did AWRE have to support GLCM?
All UK-owned warheads were essentially re-engineered from the ground up by AWE - because of the different industrial processes available from UK industry it isn't possible to just copy the US drawings and have a weapon that worked. That means any UK GLCM which isn't under dual-key arrangements needs Aldermaston to re-engineer the warhead extensively.
 
I believe that the Poseidon missiles would fit into Polaris tubes readily enough by taking out the locating rings and fibreglass liners . Also Poseidon would have the handy benefit of having more range, particularly since the Chevaline had reduced range than the Polaris A3TK.

However if the British used the Poseidon they would have to design a new MIRV warhead bus from scratch. In addition, and this is probably the biggie, the British would have to design and test an entirely new warhead and then build it in great numbers. This warhead would most likely not be able to use the ET.317 warhead designed for the Skybolt and eventually used in the Polaris A3TK and virtually identical to the WE.177 aircraft bomb.

Yep. I see this a key part of the issue. Producing the required number of warheads for Poseidon of a presumably net new design for the UK could have presented issues in my view.
 
The proposed British ones to replace the Vulcans would have had to have a British warhead under the NPT.

I seem to recall reading commentary at the time questioning the ability of the UK to produce the required number of nuclear warheads to support various contemplated UK nuclear delivery systems.

I suppose part of the what if could entail the UK deciding to invest more in their nuclear warhead design and production establishments.
 
However if the British used the Poseidon they would have to design a new MIRV warhead bus from scratch. In addition, and this is probably the biggie, the British would have to design and test an entirely new warhead and then build it in great numbers. This warhead would most likely not be able to use the ET.317 warhead designed for the Skybolt and eventually used in the Polaris A3TK and virtually identical to the WE.177 aircraft bomb.

I agree with you re the warhead production constraint but why would the UK need to design a new MIRV warhead bus from scratch if they went with Poseidon ? Presumably if they could produce enough warheads they could simply use the US version of Poseidon more or less as is ?
 
Yep. I see this a key part of the issue. Producing the required number of warheads for Poseidon of a presumably net new design for the UK could have presented issues in my view.

Don't necessarily need the same number of warheads as the US version....could just take advantage of the longer range and I think higher speed of the Poseidon.
 
Making the assumption that Poseidon isn't technically impossible for Britain here's a list of job to be done to Poseidon up the RN.


  1. Modify R class missile tubes.
  2. Purchase about 60 missiles.
  3. Design/adapt MIRV bus - some of this done on Chevaline
  4. design new warhead - done on Chevaline if possible to use the same warheads on Poseidon
  5. Build about 200-300 new warheads reusing the 180 or so existing secondaries - Chevaline built 120 or so new warheads.
  6. Test the whole shebang - done on Chevaline
That's a big job lot much of which was not done on Chevaline and will require new money that wasn't available IOTL.
 
Modify R class missile tubes.
Would that be a massive cost after all you are only copying the USN so well understood and tested ?
Purchase about 60 missiles.
Would you not have to replace missiles anyway ? What is the storage life on them ? Must be less than the 28 year service life 1968-1996 ?
Design/adapt MIRV bus - some of this done on Chevaline
Cant you use the US bus ?
design new warhead
- done on Chevaline if possible to use the same warheads on Poseidon ? You can probably even copy some of US design unlike OTL ?
Build about 200-300 new warheads reusing the 180 or so existing secondaries - Chevaline built 120 or so new warheads.
would you need more than 180 ? you could just load decoys in the rest of the spaces ?
Test the whole shebang
- done on Chevaline

I just don't see a massive cost increase and against that you keep commonalty with USN and that probably saves you cash on testing and spare parts.
 
AFAIK the USN had terminated production of the Poseidon missile by the time the British were giving the Resolution class boats their Chevaline refits.

However, the USN was refitting 12 of their first-generation SSBNs with Trident 1 at about the same time that the Resolution class boats were having their Chevaline refit.

Therefore if the UK was going to buy a better system than Poseidon it might as well be Trident I. That is on cost grounds as well as timescale, because what I have read so far makes me think that Trident 1 would not have been much more expensive than Poseidon.

That is unless the UK bought second-hand Poseidon missiles taken from the boats that were rearmed with Trident 1.
 
Don't necessarily need the same number of warheads as the US version....could just take advantage of the longer range and I think higher speed of the Poseidon.

As I understand it Poseidon was intended to deal with the Soviet ABM system by presenting a large number of warheads as valid targets that had to be intercepted. The yield of the Poseidon warheads was also fairly small by 1980's strategic nuclear standards . For both these reasons I don't believe significantly reducing the number of warheads carried by UK operated Poseidon's would have been seen as a very desirable option at the time, but I suppose some reductions might have been possible.

I do agree the added range of Poseidon would have been beneficial.

Poseidon was designed to deliver relatively a large number of fairly small warheads compared to Polaris.

If the UK chose to increase the yield of the warheads and or provide another way of defeating the ABM system then I expect the UK would have needed to embark on a R&D program that in my view would add costs and risks.
 
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From what I can tell the payload of the chevaline bus was about 400kg so the warheads are about 200kg each. The W68 of the poseidon weighed 166 kg or 1660kg all up for the payload. So presumably the poseidon bus could mount up to 8 chevaline warheads but there are only enough secondaries in the et317 stockpile to make about 200 or so chevaline warheads. So assuming that Britain went poseidon rather than chevaline they would have to download the busses to 3 warheads and even that will require maybe 60-70 more primaries than OTL. Making better use of the missile and bus to load more warheads would require even more warheads, which aren't cheap.
 
Would that be a massive cost after all you are only copying the USN so well understood and tested ?
Would you not have to replace missiles anyway ? What is the storage life on them ? Must be less than the 28 year service life 1968-1996 ?
Cant you use the US bus ?
- done on Chevaline if possible to use the same warheads on Poseidon ? You can probably even copy some of US design unlike OTL ?
would you need more than 180 ? you could just load decoys in the rest of the spaces ?
- done on Chevaline

I just don't see a massive cost increase and against that you keep commonalty with USN and that probably saves you cash on testing and spare parts.

Modifying the tubes might not be a massive cost, but it is a cost, it adds to the overall cost of the programme.

Missiles have a reasonable service life, the USN kept their Polaris missiles in service for 15 years. The British most likely didn't expect Polaris to last for 30+ years but they did plan to keep them in service for close to 2 decades and conducted servicings and relifings to keep them reliable. The 1973 flyaway cost of a Poseidon was $2.4 million US, to be spent about a decade after a they bought Polaris for about $1.5 million US. This is not a negligible cost.

I think that in the 60s a British bus was required for independence as part of the Polaris Sales Agreement. I'm sure the British could make good use of the Poseidon bus design but it would have to be different for independence purposes and because it will use British warheads.

The 120 or so Chevaline warheads reused the secondaries from the ET.317 warheads with new primaries and a new RV made of quartz phenolic. If Poseidon is purchased the British will have to do at least this much but most likely more, it will have to use all of the secondaries (which will effect the WE177C stockpile) and possibly build more if more warheads are required.

Given that even the relatively simple Chevaline went way over time and budget I think doing considerably more work to introduce Poseidon will cost even more. What's more given that Poseidon will go out of production in 1979 it won't change the obsolescence issue.
 

Delta Force

Banned
Does the RN even need new boats ? did the USN not rebuild its boats for the new missile ? How much work is involved and could the RN just rebuild its boats the same, I'm assuming the missile tubes are identical ?

(The real question is would this actually be cheaper than the historic choice of developing a unique none US system, ie 'Chevaline' ?)

Poseidon was designed as the largest missile that could fit within the standard Polaris missile launch tube. There shouldn't be any need for substantial modification of existing Polaris equipped vessels.
 
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