A smaller Sea Slug

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RAE had hopes of shrinking Sea Slug down from 20ft long, 16" diameter and wingspan of 4ft 10" to a missile of 15ft length, 12" diameter and 3ft 7" wingspan.

Assuming this had been achieved.....
It would ease demands on launcher and missile handling gear. It should also permit a greater number of missiles to be stored on a County type DDG.

This would mesh nicely with the alternative arm launchers and the later Orange Nell.
 
In what time-frame? Done late enough, all this does is demand a complete redesign of the entire launcher and handling space architecture.
 
pathology_doc said:
In what time-frame? Done late enough, all this does is demand a complete redesign of the entire launcher and handling space architecture.
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I think it's 1948 that this estimation is produced. So early enough to see Girdleness firing this instead by '58.
 
Because vertical storage is much more acceptable if it's just 2 decks high.
And arguably being that compact favours this over Thunderbird, even if it is a beam rider.
Arguably then more funds and capacity for increased production of 901 sets. Army version being much lighter without maritime features.
 
zen said:
pathology_doc said:
In what time-frame? Done late enough, all this does is demand a complete redesign of the entire launcher and handling space architecture.
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I think it's 1948 that this estimation is produced. So early enough to see Girdleness firing this instead by '58.
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Oh in that case, fine. It would be interesting to learn why this goal was not in fact achieved.
 
pathology_doc said:
zen said:
pathology_doc said:
In what time-frame? Done late enough, all this does is demand a complete redesign of the entire launcher and handling space architecture.
Click to expand...
I think it's 1948 that this estimation is produced. So early enough to see Girdleness firing this instead by '58.
Click to expand...

Oh in that case, fine. It would be interesting to learn why this goal was not in fact achieved.
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Absolutely!
Could be a mixture about doubts on guidance/warhead effectiveness and the change to solid fuel.
 
The thing I find interesting about the US 3T programme is that Terrier arose directly out of a weaponized test vehicle. The British fired RTV.1Q with a live warhead and got a drone kill, and CTV.1 against canvas-and-netting targets with direct hit potential demonstrated in the surface to surface role, but seem not to have taken the same road. RTV.1 was 16ft long, 9 inches in diameter, and weighed 500lb; however, it did use liquid propellant and would have run up against the development problems this entailed (including the development of a solid-fuel alternative and internal layout rearrangements to accommodate the typical-for-the-era centrally located motor). That being said, the relatively small size with a nominal slant range of 46k ft to an altitude of 40k ft suggests that Sea Slug could indeed have been substantially smaller than it actually was.
 
pathology_doc said:
The thing I find interesting about the US 3T programme is that Terrier arose directly out of a weaponized test vehicle. The British fired RTV.1Q with a live warhead and got a drone kill, and CTV.1 against canvas-and-netting targets with direct hit potential demonstrated in the surface to surface role, but seem not to have taken the same road. RTV.1 was 16ft long, 9 inches in diameter, and weighed 500lb; however, it did use liquid propellant and would have run up against the development problems this entailed (including the development of a solid-fuel alternative and internal layout rearrangements to accommodate the typical-for-the-era centrally located motor). That being said, the relatively small size with a nominal slant range of 46k ft to an altitude of 40k ft suggests that Sea Slug could indeed have been substantially smaller than it actually was.
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I would guess they increased range and warhead size to get to 12" despite cutting length by a foot to 15ft.
 
Of course it might have been possible to run tests between the dangers of liquid and solid rockets on ship. Decades later this was evaluated as not much difference between the options. See liquid Martel.
 
Redesigning County for your alt Seaslug doesnt make much difference to its survival. A frigate sized AA ship like T42 is all the RN can afford if it wants to build 14. Anything bigger and you are down to 6-8 hulls like T45.
Seaslug serves from 1962 to 1983 which is not bad for such a first gen system. The Countys cram in as much as you can on that design: 2 gun/1plus SSM and helo.
 
uk 75 said:
Redesigning County for your alt Seaslug doesnt make much difference to its survival.
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It might make a difference to the number of SAMs you can cram into the magazine, the size of the handling gear and the power required to drive it.

uk 75 said:
Seaslug serves from 1962 to 1983 which is not bad for such a first gen system.
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The thing I cannot understand is that Britain fielded TWO land-based SAM systems in the same general time period that used SARH, but never adapted Seaslug to it nor produced a successful wholly-indigenous radar-guided air-to-air missile (Red Dean, which probably came closest, was cancelled just before its live firing trials were due to begin).
 
pathology_doc said:
It might make a difference to the number of SAMs you can cram into the magazine, the size of the handling gear and the power required to drive it.
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Indeed
For every 3 large Sea Slug missiles you can fit 4 small Sea Slug missiles assuming horizontal storage.

It might also be of use to note the Sea Dart is not much different from small Sea Slug in absolute dimensions.

It's also easier to fit reasonable numbers on conversions of existing ships. Making the 901 the main bottleneck.

As for SAMs, Sea Slug ought to have entered service by 1956. The MkII by '60 and MkIII by '65.
MkIII seems to be SARH and led to NIGS.
 
pathology_doc said:
uk 75 said:
Redesigning County for your alt Seaslug doesnt make much difference to its survival.
Click to expand...

It might make a difference to the number of SAMs you can cram into the magazine, the size of the handling gear and the power required to drive it.

uk 75 said:
Seaslug serves from 1962 to 1983 which is not bad for such a first gen system.
Click to expand...

The thing I cannot understand is that Britain fielded TWO land-based SAM systems in the same general time period that used SARH, but never adapted Seaslug to it nor produced a successful wholly-indigenous radar-guided air-to-air missile (Red Dean, which probably came closest, was cancelled just before its live firing trials were due to begin).
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So relevant AH thread on Green Flax.
Looked at by RN in '56.

My suspicion is polyrod guidance that ended up on Sea Dart started as SARH guidance solution to giving Sea Slug such a guidance system within the constraints of the missile's design. This system seems to be one for NIGS and NIGS started as an improved Sea Slug.
Since the guidance electronics are near the rear of the Sea Slug missile body, and there's not much room in the nose. Then running cables along the sides from reciever aerials around the nose is the only way to do it.
 
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uk 75 said:
Some relevant discussion of Seaslug from nearly a decade ago.
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One of the things which consistently sticks out is the hiatus and breakup of the team working on SAMs.
It's AH scenarios all of themselves to ponder no such hiatus such as Mind the GAAP, and say pressing on with Sea Slug at Westcott.
A liquid powered Sea Slug might have entered service by the mid 50's or earlier. Despite it's issues, this would make for an earlier learning curve on SAMs.
 
More thoughts.
Fijis were studied for conversion. Suffering from stability issues due to topweight.
Smaller and lighter missiles might have helped.

GW.24 was a clean sheet Destroyer Design based on the Super Daring, but too small for the required personnel needed to man all the systems. Misdile size reduction wouldn't free enough volume I suspect.

GW.26 led to GW.29
GW.28 led to GW.32 Convoy Escort Destroyers and the last unarmoured. But capable against air, surface and submarine threats.
With Seaslug, 3"L70 twin, limbo and Type 177 and 4 twin 40mm/L70 Bofors.

The smaller lighter missile might have allowed some armour back.
That said GW.31 is potentially a better solution and a minor increase in power could have brought it upto Fleet speeds.

GW.36 to 37 provide an attractive all missile or gun and missile Cruiser with Type 984. As with other all missile ships the need for Blue Slug would be pressing, but the guns in these were the 5.25" twins.

However arguably the gun and missile GW.37 with Type 984 delivers a full AAW ship as a Design by November 1954.

GW.57 in May 1955 became the basis of the County class and submitted November '55 which ironically was the same time Design Staff limitations meant only one magazine system was achievable.
Sketch design approval was 11 April 1957

A smaller lighter and potentially easier to store vertically missile might have changed the outcome here.
In fact by '59 vertical loaders were schemed.

Had Smaller Seaslug won Army funding it's likely that the system would achieve operational earlier, funding not being diverted away to Thunderbird.
This might in turn free up funds for Orange Nell......as was expected IRL.
 
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The profile of non US NATO navies air defence ships puts the UK effort in perspective.
Only France deployed its own medium range naval SAM. Masurca was closer to Terrier in concept and France did purchase 4 Tartar systems for its destroyers. Only three Masurca systems made it into service compared with 8 Seaslugs.
Terrier was the only alternative but its cost limited its use to one Dutch and three Italian cruisers.
Persisting with the Seaslug in its heavy variant and not changing it worked for numbers.
Seadart proved even more numerous and equipped nearly twenty ships (allowing for unbuilt T42s). No other Western European country had this number of systems.
Only the Japanese could afford to buy Standards in anything like these numbers.
 
pathology_doc said:
In what time-frame? Done late enough, all this does is demand a complete redesign of the entire launcher and handling space architecture.
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Even done early, it doesn't make that much difference. The fundamental difference in stowage density between Terrier and Sea Slug was fins. The Royal Navy took the view that installing fins would unacceptably slow the rate of fire, so missiles had to be stored with them installed. That defined the size of the missile envelope.

The USN believed that installing fins as part of the loading process was acceptable, which meant that the envelope for Terrier could be much smaller, and the missiles stowed more densely.

This is why Sea Slug's wraparound boosters are often mentioned reducing volume: they fit within the envelope defined by the fins. If you store finless missiles, then tandem boost becomes more space efficient.

Performance-wise, of course, there wasn't much to pick between Sea Slug and early Terrier. They were both, frankly, a bit crap. But the US could afford a series of upgrades to Terrier, which significantly improved its capability. The UK couldn't.
 
At this point one could ask - why didn't they use flip-out fins?
 
Presumably, that technology wasn't thought sufficiently mature at the time. I'm not sure when flip-out fins first came into use - possibly with Harpoon, at least in the West?
 
Flip-out fins were mainly on rockets (R4M, FFAR) at this time, but Blue Danube had flip-out fin extensions and as one missile example, in the US the GAR-9B/AIM-47 was developed with flip-out fins in 1960, so the know-how was becoming available I would think.

Even so, there is no denying that quad-packing four Goslings into the fin diameter was a neat solution, the question is was there an alternative booster that could offer the same thrust as four Goslings in a tandem? Remember that Sea Slug could coast for 6,000yd, 50% longer than the equivalent Terrier of the time.
The result would either be a tandem missile/booster combination around 9m (ish) long which would be more or less Terrier sized (though 3in wider diameter).
 
Hood said:
Even so, there is no denying that quad-packing four Goslings into the fin diameter was a neat solution, the question is was there an alternative booster that could offer the same thrust as four Goslings in a tandem? Remember that Sea Slug could coast for 6,000yd, 50% longer than the equivalent Terrier of the time.
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If nothing else, the Nike-Hercules option of bundling four Goslings together would presumably be feasible, without excessive diameter.
 
Hood said:
At this point one could ask - why didn't they use flip-out fins?
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Because Terrier, Talos and Seaslug were first-generation baby-steps missiles. They had enough trouble getting them to work at all, let alone add sophisticated gimmicks onto them.
 
uk 75 said:
Persisting with the Seaslug in its heavy variant and not changing it worked for numbers.
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However the potential in this AH is for the Army to also go down this route instead of waiting for Thunderbird.
The key question there is over the need for Type 901 missile guidance and target tracking radar.
It might have been a case of developing the Type 902 from a gathering set, into a lightweight alternative.

Yellow Palace said:
Performance-wise, of course, there wasn't much to pick between Sea Slug and early Terrier.
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You've not looked at the saved record then on Seaslug.
 
zen said:
You've not looked at the saved record then on Seaslug.
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Note the key word, early. Seaslug was crap when it entered service. So was the original beam-riding Terrier. Both had underwhelming performance and appalling reliability. Of the two, Seaslug had about 50% more range, a 50% higher ceiling, but weighed twice as much. The Terrier was improved to the point where it became a useful weapon. Seaslug, not so much - even with the usual five year lag fom the US to the UK - and remained crap until it was finally retired.

An imagined Seaslug improvement plan along the lines of that which Terrier received might plausibly give you a Mark 4 missile entering service in 1967-1968 with solid-state electronics, semi-active homing, and a range in the region of 60 nautical miles.
 
Tandem is a possibility, but excludes vertical stowage as it would bring length over the IRL missile's 20ft.

Certainly motors for Thunderbird were something around 19-20" diameter, so bundling Goslings together seems pointless if one does go tandem.

Whereas a 15ft long weapon fits into two decks of 8ft each for a magazine of 16ft height.
If the weapon was 16ft long this might still be accommodate-able if one of the decks was higher, as might be the case for beams or magazine facilities in the gun and torpedo storage sections.
Certainly when designing the 1952 carrier, magazine deck was higher to accommodate such handling gear for weapons.

A magazine system able to cope with 15ft long Seaslug actually ought to manage the shorter Orange Nell. Diameters now being much closer as would overall 'missile and boosters' 'box'.
Though it might be the case ON could then utilise a tandem arrangement and still be short enough.

It's also possible if one of the alternative twin arm launchers was used that Tartar could become an option if the magazine system is for 15ft long missiles.
Which means both Sea Dart and Standard might fit......

The obvious 'easy' (it's not but nothing is) would be to fully separate beam projecting Missile Guidance Radar, from Target Tracking Type 901. This would allow predictive interceptions and more efficient flightpaths. More demand on the computers though.
 
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A smaller Seaslug would just be a shorter-range Seaslug carrying a smaller warhead, if developed on the same timeline. To extract better performance from the type one or both of two things need to happen:
  1. The decisions of two successive First Sea Lord's (Rhoderick McGrigor and Mountbatten) with regards to the future building programme need to be different to the extent that ships designed around Seaslug, rather than with Seaslug shoehorned into them, are built (the vast majority of the GW series designs).
  2. Interest in continued development of Seaslug needs to be sustained. In reality, as early as 1954 a working party had concluded that something in a different class altogether was needed for the future, so Blue Envoy became the future system whilst Seaslug became a single generation interim weapon - right up until Blue Envoy was cancelled and Sea Slug Mk.2 emerged as a, relatively uninteresting, interim system to NIGS (which was basically a Blue Envoy replacement for the RN).
 
It's not a complete given such an assertion.
The warhead increase was obviously driven by concerns over accuracy and resulted in Girdle Ness having the intended triple launcher.

It was also clear that there was a push to get something out ASAP. Ironic considering the subsequent delays.
Very Ironic considering the size of missile became a significant factor in scuppering plans for rebuilding some cruisers with it.
Which also scuppered plans for making the missile vertical launch.

The larger the warhead, the greater the missile size for a given level of pk at specified range/altitude limits.

Actual firings proved a higher accuracy and thus the twin launcher.
But likely too late to change.

The other aspect we've touched on elsewhere in greater depth was the solid rocket fuel formulas. UK lagged behind the US in this aspect.

Arguably the accuracy could have allowed the smaller warhead and thus smaller missile.

15nm for a 15ft long missile is still rather short range.
 
Seaslug wasn't especially delayed, from 1949 onwards it was seen as a system ready for ship-fitting in the 1957+ timeframe, hence it appearing on "1960" cruiser concepts in 1949. That timeline, and the available R&D resources, did drive some decisions, e.g. it is part of the reason why it was beam-riding and not semi-active radar homing, but compared to some other programmes it wasn't particularly delayed.

There were never any serious plans for converting existing cruisers. Periodically a senior officer would travel to the US, hear about or see the US cruiser conversions (e.g. the Bostons and Galvestons) and then muse as to whether the RN could do something similar with its existing ships. The answer was always the same, the level of work required to convert an existing ship (complete rearrangement of internals, new electrical system, additional generating capacity, etc.) was prohibitive. Additionally, the ships would be nearing the end of their theoretical hull lives by the time the work was done, and the hulls didn't really have enough volume. The USN had a glut of unfinished or very young, comparatively high volume, cruiser hulls at the end of the war. The RN didn't, the few modern cruiser hulls it had were relatively small having been designed to, or evolved from, treaty compliant designs. The well-known Fiji proposal has been given far more credence than it deserves, it was almost certainly drawn for the sole purpose of demonstrating it wasn't a good idea and to nudge decision making in the direction of new construction GW ships.

The real opportunity with Seaslug is for a bigger missile. The Seaslug handling system could handle a larger missile, the limiting factor was the launcher. This was explored during the process that lead to Seaslug Mk.II. By replacing the launcher (which probably explains the twin arm launcher models in photos at the Barrow Dock museum) a larger, longer-ranged, missile could have been adopted. This was proposed but wasn't pursued and the actual Seaslug Mk.II was built within the dimensions and aerodynamic configuration of the Mk.I. In an AU world, combine this larger missile with continued development of the homing head included in the design for a period in the early 1950s and a very interesting weapon for the early 1960s is possible.

The ideal Seaslug ship system used two GMS.1 guidance systems, as this matched the number of engagements to the launcher reload cycle, combined with a Type 984 3D radar. A double-ended configuration (e.g. two Seaslug launchers and four GMS.1 systems) was preferable. My AU optimal Seaslug ship would use this configuration with a pair of Seacat systems, a 32 or 48 track CDS system, no armour or guns and as many Seaslugs as could be carried with that equipment with the two shaft 90,000shp (60,000 SHP steam, 30,000 SHP GT) machinery proposed as part of the Y102 studies. This would produce something akin to a British Leahy.
 

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