Sea Wolf and Sea Dart: Unbuilt Derivatives and Cancelled Applications

[NMaude]

Never heard of an ABM Sea or Land Dart, guidance would have been marginal and it was a bit slow for such a rapidly incoming target.

The Brits could've obtained the design for the W81 (Designed to replace the RIM-2D's W45 warhead, it was designed to fit in a 13.5" airframe).

 

[bobthemonkey]

If memory serves, the Fort Victorias were originally specced with VL Sea Wolf because they were intended to operate in the GIUK gap as the central ship of a small hunting group based on austere ASW frigates (can't remember if that was the initial cuts of Type 23, or Type 24 or 25), which rather put them in harms way. Type 23 evolved to be rather more capable, allowing the Fort Victorias to have a less exposed role, and VL Seawolf to be cut.

Correct, but the VLS did carry through to the produced design. While the missile guidance hardware was, AIUI, never installed, the VLS silo was built, and individual hatch covers installed, which are still present in this 2018 photo (albeit with a new satcom dome bolted on top!)

RFA Fort Victoria modified to support the aircraft carriers | Navy Lookout

www.navylookout.com

 

[Zoo Tycoon]

The Brits could've obtained the design for the W81 (Designed to replace the RIM-2D's W45 warhead, it was designed to fit in a 13.5" airframe).

Sea Dart had an 11 Kg warhead that was located aft of the conical aerospike inside the component known as the forebody. While the forebody was approx 10 inch diameter this included a layer of insulation, required due to kinetic heating, so the useful diameter was maybe 8-9 inches. The W45 is reported to weigh 68kg which would made a real mess of the missiles weight and balance. As said before such a warhead would need to be located somewhere else on the airframe…. Which is difficult considering everything aft of the forebody was an annular section;- the air for the ramjet flows through a central tube approx 8 inches diameter.

 

[Dilandu]

Hm. Putting any kind of heavier warhead here would be problematic. The only approach seems to increase the lenght of central interbody rearward, and try to balance 50+ weight increase with moving fuel tanks backward?

 

[NMaude]

The W45 is reported to weigh 68kg which would made a real mess of the missiles weight and balance.

I was talking about the W81 not the W45, now if the W81's diameter (~12") was to big then the RN could've looked at a 6" or 8" liner-implosion warhead of the sort used in US Army nuclear artillery-shells.

 

[Yellow Palace]

The Brits could've obtained the design for the W81 (Designed to replace the RIM-2D's W45 warhead, it was designed to fit in a 13.5" airframe).

The W81 seems to have been based on the Cougar primary, which shares heritage with the Cleo primary in the UK's PT.176. The shared first letter isn't a coincidence - note that Tsetse became Tony when Anglicised, and Python became Peter. In fact, there's some evidence that the multi-point initiation system used by both Cougar and Cleo was first developed at Aldermaston.

The 2 kt yield for the OR.1176 warhead (which became PT.176) was dropped in 1963, which is before the date of this document. W81 design work started in 1976, which is far too late.

Design resource limitations would probably rule out a new (linear implosion?) warhead - even based on a US design - while diameter and weight would seem to rule out a PT.176 derivative.

 

[Scott Kenny]

The W81 seems to have been based on the Cougar primary, which shares heritage with the Cleo primary in the UK's PT.176. The shared first letter isn't a coincidence - note that Tsetse became Tony when Anglicised, and Python became Peter. In fact, there's some evidence that the multi-point initiation system used by both Cougar and Cleo was first developed at Aldermaston.

The 2 kt yield for the OR.1176 warhead (which became PT.176) was dropped in 1963, which is before the date of this document. W81 design work started in 1976, which is far too late.

Design resource limitations would probably rule out a new (linear implosion?) warhead - even based on a US design - while diameter and weight would seem to rule out a PT.176 derivative.

Also, linear implosion tends to be heavy for the yield, can't really get the proper squeeze on anything but a spherical primary.

And that further messes up our weight and balance on the missile.

 

[zen]

Didn't someone do a two point initiation design?
Lower diameter if I reccal the benefits

 

[NMaude]

Also, linear implosion tends to be heavy for the yield, can't really get the proper squeeze on anything but a spherical primary

True however a) a linear implosion warhead for Sea Dart would be a LOT lighter as it doesn't have to deal with the multi-hundred G-loads the setback subjects a shell too and b) for an air-to-air role the warhead doesn't;t to be that powerful, IIRC the W30 warhead the Tacos used was only 0.5KT in yield.

Didn't someone do a two point initiation design?
Lower diameter if I reccal the benefits

The W45 used a two-point air-lens design IIRC.

 

[Scott Kenny]

True however a) a linear implosion warhead for Sea Dart would be a LOT lighter as it doesn't have to deal with the multi-hundred G-loads the setback subjects a shell too and b) for an air-to-air role the warhead doesn't;t to be that powerful, IIRC the W30 warhead the Tacos used was only 0.5KT in yield.

5kt in the Talos. 0.5 KT for Tactical Atomic Demolition Munition.

But let's look at the W54, as used in the AIM-26 Falcon. 280mm diameter, 400mm long, and 23kg. It's still probably a little overbuilt, since the same basic design was also used in the Davy Crockett nuclear artillery. 0.25kt yield.

But I don't think you'll find a warhead that light in less than 200mm diameter.

 

[datafuser]

From a web search some years ago - The Type 1030 STIR. The unit was undergoing tests for some time at the then A.S.W.E. (Admiralty Surface Weapons Establishment) - since undergone several re-namings, it later became part of A.R.E. (Admiralty Research Establishment) and now I think it is part of the organisation called Qinetiq, on Portsdown Hill just north of Portsmouth U.K.
I used to live in Portsmouth and recall seeing it on its mast when you drove past.

I took that picture from a 1973 Navy International at the SAFTI Military Institute Library in 2003.

This picture brings back a lot of good memories...

 

[Hood]

There were some other early Sea Dart layouts though from the proposed SSM version; one with a fatter 18.9in diameter body for a 250lb warhead and another which had no ramjet and combined sustained/booster rocket motor.

Can only surmise whether any of these layouts were proposed for the nuclear Sea Dart.

 

[Firefinder]

5kt in the Talos. 0.5 KT for Tactical Atomic Demolition Munition.

But let's look at the W54, as used in the AIM-26 Falcon. 280mm diameter, 400mm long, and 23kg. It's still probably a little overbuilt, since the same basic design was also used in the Davy Crockett nuclear artillery. 0.25kt yield.

But I don't think you'll find a warhead that light in less than 200mm diameter.

The US Army 155mm nukes like the W48 will do.

At 54 kg, with 20 of that being the shell casing, it was test shot up to 500 tons of TnT. Plus it was expected to be use in an Anti Air Artillery role being able to be set off up to 50k feet.


The later W82 warhead came in at 43 kg with a Rap booster and had a 2 kiloton yield. But was cancel in 1991 due to Peace divide.

The USN SWIFT warhead was a 1960s attempt at a 1 kiloton 5 inch diameter Thermonuclear device. Due to some bad manufacturing it fizxled out at 250 tons in testing.

Theres a few other sub 200mm devices that the Army and Navy fuck with in the Early cold war that everyone forgotten bout.

 

[Zoo Tycoon]

The other factor to keep in mind was the British mid sixties Pu shortage. The 1957 Windscale fire and its aftermath had severely limited Pu production at a time of significant demand expansion to cope with Polaris. Windscale was the sole specialty manufacturing source for British Pu and it took a long time to bring on the Magnox special irradiation channels. The prospect of making hundreds of even small warheads would have been well beyond the stockpile or capacity. I think this is often underestimated as reason for the dropping of plans for Sea Slug, Bloodhound, Blue Water and Thunderbird.

 

[Yellow Palace]

The other factor to keep in mind was the British mid sixties Pu shortage. The 1957 Windscale fire and its aftermath had severely limited Pu production at a time of significant demand expansion to cope with Polaris. Windscale was the sole specialty manufacturing source for British Pu and it took a long time to bring on the Magnox special irradiation channels. The prospect of making hundreds of even small warheads would have been well beyond the stockpile or capacity. I think this is often underestimated as reason for the dropping of plans for Sea Slug, Bloodhound, Blue Water and Thunderbird.

Did the fissile material shortage caused by Windscale shutting down in 1957 last as long as that? The Magnox production plants at Calder Hall and Chapelcross came online between 1956 and 1960, and certainly by 1960 the MoD was cheerfully writing plans that called for several hundred warheads a year.

While those numbers were pie in the sky, they do suggest that an easing of the fissile material shortage from 1963 was envisaged.

 

[Zoo Tycoon]

Did the fissile material shortage caused by Windscale shutting down in 1957 last as long as that? The Magnox production plants at Calder Hall and Chapelcross came online between 1956 and 1960, and certainly by 1960 the MoD was cheerfully writing plans that called for several hundred warheads a year.

While those numbers were pie in the sky, they do suggest that an easing of the fissile material shortage from 1963 was envisaged.

I understand although Calder Hall and Chappel cross came on line at those dates, the Pu production was quite different to the Windscale piles. The Magnox used a ring of dedicated fuel channels rather than the create PU with the whole fuel mass. Pu 239 needs a 25-28 day reaction, which is relatively straightforward if you have a fully dedicated pile, just fill, react, empty and repeat. However Magnox was designed to provide both continuous power and Pu 239 inserted and extracted from the channels on a regular basis…. But it wasn’t straightforward when piggybacking on to a power reactor, it took a few years to fine tune the process with yields being much lower than expected. Eventually it came good but I understand in the early to mid sixties there was a lot of uncertainty about just how much would be produced.

 

[Yellow Palace]

But it wasn’t straightforward when piggybacking on to a power reactor, it took a few years to fine tune the process with yields being much lower than expected. Eventually it came good but I understand in the early to mid sixties there was a lot of uncertainty about just how much would be produced.

That would make sense. It also partly explains why the second half of Chapelcross wasn't built, and why the three commercial plants designed to run a military cycle were never used that way. By the time the wrinkles in production had been worked out, the need for a tonne or two of plutonium a year had gone away.

 

[NMaude]

The USN SWIFT warhead was a 1960s attempt at a 1 kiloton 5 inch diameter Thermonuclear device. Due to some bad manufacturing it fizxled out at 250 tons in testing.

The SWIFT device was a UCRL design tested in operation Redwing in 1956, from Carey Sublette's Redwing page:

Test:	Yuma
Time:	19:56 27 May 1956 (GMT) 07:56 28 May 1956 (local)
Location:	Eniwetok Atoll, Aomon (Sally) island
Test Height and Type:	205 Foot tower
Yield:	0.19 kt

This was a UCRL linear implosion design intended for air defense warheads. The device, known as Swift, was a boosted asymmetrical design. The device failed to boost however, and the yield was far below predictions. The Swift was only 5 inches in diameter, and 24.5 inches long, and weighed 96 lb. This was the smallest diameter, and lightest nuclear device tested up to this time. It used Octol 76/24 as the explosive and was presumably a plutonium fueled device.

 

[Scott Kenny]

The US Army 155mm nukes like the W48 will do.

At 54 kg, with 20 of that being the shell casing, it was test shot up to 500 tons of TnT. Plus it was expected to be use in an Anti Air Artillery role being able to be set off up to 50k feet.


The later W82 warhead came in at 43 kg with a Rap booster and had a 2 kiloton yield. But was cancel in 1991 due to Peace divide.

The USN SWIFT warhead was a 1960s attempt at a 1 kiloton 5 inch diameter Thermonuclear device. Due to some bad manufacturing it fizxled out at 250 tons in testing.

Theres a few other sub 200mm devices that the Army and Navy fuck with in the Early cold war that everyone forgotten bout.

And they're still massively heavy.

Remember, the warhead in Sea Dart is only 11kg(!!!).

We can probably get away with a W54 that's 23kg if we add some ballast to the tail feathers and maybe enlarge them. No way we are getting away with 34kg of W48 or Swift.

 

[NMaude]

We can probably get away with a W54 that's 23kg

IIRC the bare W54 (Without the Davy Crockett projectiles aerodynamic fairing and the firing set electronics) weighed 35Lb

 

[zjz]

I took that picture from a 1973 Navy International at the SAFTI Military Institute Library in 2003.

This picture brings back a lot of good memories...

Talking about a 1973 magazine found in 2003 in the year 2024

Is the STIR design typical for the radar antenna?

 

[Yellow Palace]

IIRC the bare W54 (Without the Davy Crockett projectiles aerodynamic fairing and the firing set electronics) weighed 35Lb

The UK had been interested in the W54 - the UK version was 'Wee Gwen' - with an estimated weight of 50-55 lb and a yield of 37 tons. The W54 Mod 0 used on the AIM-26 Falcon was 50.9 lbs and had a yield of 250 tons; it's probably the closest match to what a Sea Dart warhead would require.

Crucially for this application, Wee Gwen would have had diameter of 10.75 inches, and W54 Mod 0 was only a little larger.

Somewhat amusingly, Wee Gwen was planned to be deployed with the 'David Crockett' weapon system. I imagine that 'Davy' was much too informal for the British officer class to tolerate. This was the weapon that accounted for the 'several hundred warheads a year' plans I mentioned above, and seems to have been dropped by February 1962.

Incidentally, these plans seem to peak at 790 kg of plutonium a year in 1966-1967, or 580 kg if a low-yield version of Tony (the Anglicised W44 Tsetse) was used instead of Wee Gwen. Making some very crude estimates, UK plutonium production likely peaked at around 375 kg per year.

 

[A Tentative Fleet Plan]

The UK had been interested in the W54 - the UK version was 'Wee Gwen' - with an estimated weight of 50-55 lb and a yield of 37 tons. The W54 Mod 0 used on the AIM-26 Falcon was 50.9 lbs and had a yield of 250 tons; it's probably the closest match to what a Sea Dart warhead would require.

Crucially for this application, Wee Gwen would have had diameter of 10.75 inches, and W54 Mod 0 was only a little larger.

Somewhat amusingly, Wee Gwen was planned to be deployed with the 'David Crockett' weapon system. I imagine that 'Davy' was much too informal for the British officer class to tolerate. This was the weapon that accounted for the 'several hundred warheads a year' plans I mentioned above, and seems to have been dropped by February 1962.

Incidentally, these plans seem to peak at 790 kg of plutonium a year in 1966-1967, or 580 kg if a low-yield version of Tony (the Anglicised W44 Tsetse) was used instead of Wee Gwen. Making some very crude estimates, UK plutonium production likely peaked at around 375 kg per year.

Gwen was certainly planned to be used with NIGS, see the bottom row of the table in this document from Brian Burnell's site:

 

[Yellow Palace]

Gwen was certainly planned to be used with NIGS, see the bottom row of the table in this document from Brian Burnell's site:

That's the table I'm referring to... I've always read that as Owen, and figured it was some future warhead that hadn't been defined yet!

 

[A Tentative Fleet Plan]

XWRI STIR (SURVEILLANCE TARGET INDICATING RADAR): EXPERIMENTAL SYSTEM ON HMS GRENVILLE [Allocated Title]

The installation of the XWRI STIR (Surveillance Targer Indicating Radar) experimental system on HMS Grenville, Portsmouth, in 1972.

www.iwm.org.uk

 

[A Tentative Fleet Plan]

Some information on couple of planned Sea Wolf variants here, including an image of the proposed GWS-27 tracker:

Seawolf Sitrep

Seawolf Sitrep. December 1986. LIEUTENANT-COMMANDER R. J. EDWARDS, M.Sc., C.ENG., M.I.E.E., R.N.

library.imarest.org