Updating Seaslug

[uk 75]

By the mid 1970s the Royal Navy had 8 modern area defence DLGs in service. This was more than any other W European Navy.
But the Seaslug system used obsolete missiles and guidance.
There was plenty of space in the County class for a horizontal assembled and launched missile to replace Seaslug.
Could this have been done?

 

[bobtdwarf]

By the mid 1970s the Royal Navy had 8 modern area defence DLGs in service. This was more than any other W European Navy.
But the Seaslug system used obsolete missiles and guidance.
There was plenty of space in the County class for a horizontal assembled and launched missile to replace Seaslug.
Could this have been done?

The Egyptian proposal was replace sea slug with sea dart. Looking at the dimensions of the two looks plausible

 

[Rule of cool]

Why does the missile itself need to be replaced, rather than a comprehensive upgrade with late 60s electronics and rocket propellants to replace the mid 50s gear?

What about the radars, the Sea Slug needed the Type 965 AKE2 search, Type 992Q target indicator, Type 278 height finder and Type 901M guidance radars. Could that be reduced with late 60s electronics in the missile?

 

[Dilandu]

There was plenty of space in the County class for a horizontal assembled and launched missile to replace Seaslug.

It was not that simple. The missile magazines of County-class were very long and narrow. The missiles were stored in two "lanes", one after another.

Repurposing this space for some other missiles would be a major headache. For example, we couldn't just swap Seaslug for Terrier, because old Seaslug magazines are too narrow to install the Terrier's usual horizontal drums.

So basically the problem is: to put any other naval SAM on County-class, we would be be forced to either reconstruct the ship whole stern section (which would likely demand the hangar removal), or design a SAM magazine that would fit into old Seaslug space (which would preclude the use of existing systems)

 

[Dilandu]

The Egyptian proposal was replace sea slug with sea dart. Looking at the dimensions of the two looks plausible

Sea Dart, if I recall correctly, could not be stored horizontally. And its launchers were designed to be reloaded verically from below. So even if we managed to put Sea Dart conveyor-type magazine into Seaslug space (which would be problematic - the ceiling is too low for 4.5 meters missile standing on its tail), we would still need to place the launcher atop the magazine (which would block the helicopter deck completely)

 

[Dilandu]

Why does the missile itself need to be replaced, rather than a comprehensive upgrade with late 60s electronics and rocket propellants to replace the mid 50s gear?

What about the radars, the Sea Slug needed the Type 965 AKE2 search, Type 992Q target indicator, Type 278 height finder and Type 901M guidance radars. Could that be reduced with late 60s electronics in the missile?

Well, if we install on Seaslug a two-mode boost-sustain motor and SARH homing (presumably of interferometer type, albeit it may be possible to put a small dish seeker into nose cone), it could be made reasonably close to Terrier in performance.

 

[zen]

Well we start with the doomed Seaslug MkIII that drifted off into NIGS and so we can certainly see the basis of a SARH upgrade on the missile by using a polyrod interferometer seeker. Which externally might impact the Type 901 system most to give it SARH guidance.
Possibly one could lift the Sea Dart seeker onto such a development of Seaslug and replace the Type 901 with Type 909

It's not impossible within the dimensional constraints of the magazine system to develop an alternative new missile, and again this would effect externally the TIR system.
Such a missile might even be a linear two stage type. After all the system handles a 19ft long missile.

We can see Blue Slug offered an Anti-ship Missile option and future developments could again fit.

And it's not impossible to develop a ballistic missile option. Much like the abortive Taurus development of Terrier.

So you could extract quite an improvement.

A change in the launcher is also possible as is modification of the magazine system. Shorter missiles such a variant of Sea Dart built to be stored on it's side for example.

 

[Dilandu]

Well we start with the doomed Seaslug MkIII that drifted off into NIGS and so we can certainly see the basis of a SARH upgrade on the missile by using a polyrod interferometer seeker

Theoretically, a very compact dish seeker - like on AIM-9C (the radar-homing version of Sidewinder) - could be installed under Seaslug enlarged nose cone. Though I need to check the schematics to be sure.

 

[Hood]

Well there are eight ships, so that provides a reasonably large basis to justify an upgrade, but refitting eight ships with a new missile, magazine alterations, new radars, ADAWS etc. costs a lot of money.
So you need an upgrade that is relatively cheap so that eight sets of kit don't break the bank and disrupt the Sea Dart programme.

I think a cleaned up, modernised Sea Slug with a decent booster stage so that it doesn't have the four boosters would be pretty useful. Nothing wrong in using Sea Dart's fire-control systems. Of course the question then is, why not just use Sea Dart?

Technically I guess you could simply engineer a horizontal Sea Dart magazine system with a modified twin-arm launcher. There were already at least three different launchers and magazines in existence for Sea Dart so a fourth might not matter...

 

[Dilandu]

I think a cleaned up, modernised Sea Slug with a decent booster stage so that it doesn't have the four boosters would be pretty useful. Nothing wrong in using Sea Dart's fire-control systems. Of course the question then is, why not just use Sea Dart?

The change in booster arrangement would require perry big redesign on launcher & handling system. Frankly, my opinion - it's not worth the time and efforts. The minimal practical refit, IMHO:

* A SARH homing system - either interferometer-type (to ensure commonality with Sea Dart) or small dish seeker (probably would require two-stage guidance - beam-riding close to target, SARH for terminal homing)
* A boost-sustain rocket motor - for greater range & thrust

 

[GK Dundas]

The change in booster arrangement would require perry big redesign on launcher & handling system. Frankly, my opinion - it's not worth the time and efforts. The minimal practical refit, IMHO:

* A SARH homing system - either interferometer-type (to ensure commonality with Sea Dart) or small dish seeker (probably would require two-stage guidance - beam-riding close to target, SARH for terminal homing)
* A boost-sustain rocket motor - for greater range & thrust

It's certainly a complete waste of time, effort and money....I surprised the British didn't fall all over themselves trying to do then .

 

[Dilandu]

It's certainly a complete waste of time, effort and money....I surprised the British didn't fall all over themselves trying to do then

I disagree. The waste of time and money was the decision NOT to upgrade Counties, replacing them with less capable units.

 

[NOMISYRRUC]

Well we start with the doomed Seaslug MkIII that drifted off into NIGS and so we can certainly see the basis of a SARH upgrade on the missile by using a polyrod interferometer seeker. Which externally might impact the Type 901 system most to give it SARH guidance.
Possibly one could lift the Sea Dart seeker onto such a development of Seaslug and replace the Type 901 with Type 905.

It's not impossible within the dimensional constraints of the magazine system to develop an alternative new missile, and again this would effect externally the TIR system.
Such a missile might even be a linear two stage type. After all the system handles a 19ft long missile.

We can see Blue Slug offered an Anti-ship Missile option and future developments could again fit.

And it's not impossible to develop a ballistic missile option. Much like the abortive Taurus development of Terrier.

So you could extract quite an improvement.

A change in the launcher is also possible as is modification of the magazine system. Shorter missiles such a variant of Sea Dart built to be stored on it's side for example.

Is Type 905 a typo for Type 909? As far as I know Type 905 was the radar associated with the MRS.5 digital fire control system and both were cancelled in the late 1940s defence cuts when Britain's Post-War Austerity Era became even more austere.

 

[Dilandu]

Well, it's the closest thing to the Seaslug launcher (three-rail one) I was able to model:



The darn thing is ABSURD. It's overcomplicated to utterly ridiculous level. I just fail to see, what was the point of this lattice construction, and why a simple upper rail (or launch tube, if they wanted missile enclosed) can't be used instead. The pedestal mount is also ridiculously overcomplicated; I just can't figure out what some parts are supposed to do!

 

[Hood]

In light of the above post - worth noting we have a rearmed County thread - https://www.secretprojects.co.uk/threads/rearming-the-county-class-missile-ships.41283/

 

[zen]

Is Type 905 a typo for Type 909? As far as I know Type 905 was the radar associated with the MRS.5 digital fire control system and both were cancelled in the late 1940s defence cuts when Britain's Post-War Austerity Era became even more austere.

Sigh....yes Type 909 Desertcar.

As an aside we now know that Type 901 was named Jelly.

 

[Rule of cool]

Seaslug required 4 radars to work because a 3D radar wasn't available, the Type 984 would have require the removal of the guns so it wasn't fitted. What about the solid state version of the Type 984, the 985? IIUC the 985 was the 984 with the vacuum tube electronics replaced with the much smaller solid state kit and the 4 feed horns that moved 5 degrees with servos to provide the height finding capability fixed and changes in frequency being used to get the 5 degrees vertical scanning. If fitted to the County's it would replace 3 radars: 965, 992 and 278 and make the Seaslug a more capable system in general.

 

[zen]

The only references I've got to Type 985 suggest it's a four face PESA system.

We also have something called Trackwell. Which is likely a direct parallel to the multirole Typhon radar.

Now it's theoretically possible for the SSSR effort that resulted in ASWRE C-band 3D radar proposal, which was abandoned for political reasons for the Dutch Type 988 Broomstick. Could become the upgrade to the Countys.

 

[NOMISYRRUC]

Seaslug required 4 radars to work because a 3D radar wasn't available, the Type 984 would have require the removal of the guns so it wasn't fitted. What about the solid state version of the Type 984, the 985? IIUC the 985 was the 984 with the vacuum tube electronics replaced with the much smaller solid state kit and the 4 feed horns that moved 5 degrees with servos to provide the height finding capability fixed and changes in frequency being used to get the 5 degrees vertical scanning. If fitted to the County's it would replace 3 radars: 965, 992 and 278 and make the Seaslug a more capable system in general.

@Hood has some interesting things to say on that subject in the rearming the County class thread that he put a link to in Post 15.

 

[GK Dundas]

I disagree. The waste of time and money was the decision NOT to upgrade Counties, replacing them with less capable units.

Actually I do tend to agree with you on the Need to keep the Counties useful for as long as possible.
I'm just not too sure if you can even store a Sea Dart horizontally to begin with.
Mind you I wonder how expensive it would be to place a launcher and magazine in the space occupied by the B turret.
Granted it would be a small magazine. How much below deck space did the Launcher/magazine for the Sea Dart used on the Batch 1 T - 42 take ?
I swear I seen artwork for something along these lines somewhere.

 

[Scott Kenny]

The obvious steps to improve the missile are:
1) polyrod interferometer ala Talos and Sea Dart
2) new rockets, buy the Terrier/Tartar solid chemistry off the Americans.
3) updated radars

 

[Rule of cool]

The obvious steps to improve the missile are:
1) polyrod interferometer ala Talos and Sea Dart
2) new rockets, buy the Terrier/Tartar solid chemistry off the Americans.
3) updated radars

That sounds like good value for money upgrade that wouldn't endanger new construction.

 

[Dilandu]

Actually I do tend to agree with you on the Need to keep the Counties useful for as long as possible.
I'm just not too sure if you can even store a Sea Dart horizontally to begin with.

Actually, it seems to be possible. I refreshed my memory about this tread - and the container box launcher for Sea Dart was suggested and even tested. So, it seems that horizontal storage is not impossible:



If the Sea Dart could be stored horizontally, then it is likely possible to rebuild the old Seaslug magazines on Counties for new missiles. Since Sea Dart did not require assembly & could be stored complete, we could use all length of magazine system to store ready-to-use missiles. Since Sea Dart is about 1/3 smaller than Seaslug, we could put at least as much missiles onboard the County as on the Type 42 (i.e. 30)

Hovewer, using Sea Dart with horizontal storage would require some launcher redesign. It must be modernized to allow horizontal (or at least angled) loading. I doubt it would require too much efforts, though.

 

[CV12Hornet]

Given the RN's manpower woes throughout the postwar era, I don't think keeping the Counties longer is a good idea. They required 450 crew, a very high number for their size and role.

 

[Dilandu]

Given the RN's manpower woes throughout the postwar era, I don't think keeping the Counties longer is a good idea. They required 450 crew, a very high number for their size and role.

Well, it's about 2 times more than Batch 1 Type 42 destroyer and about 50% more than Batch 3. But Counties are bigger and more capable in general. Some automatization features may be also implemented to reduce the number of crew required.

 

[Rule of cool]

Automation needs to be designed in to a ship, its difficult and expensive to refit a ship with it.

 

[bobtdwarf]

t

Sea Dart, if I recall correctly, could not be stored horizontally. And its launchers were designed to be reloaded verically from below. So even if we managed to put Sea Dart conveyor-type magazine into Seaslug space (which would be problematic - the ceiling is too low for 4.5 meters missile standing on its tail), we would still need to place the launcher atop the magazine (which would block the helicopter deck completely)

yeah I was also under the same impression.. still they were trying to sell Egypt a County with horizontal storage. So either what we have both read online is incorrect (possible, very possible), or they had a fix.

Edit because I went and looked up the data I dang well and going to post it lol
SeaDart

Mass	550 kg (1,210 lb)
Length	4.4 m (14 ft)
Diameter	0.42 m (17 in)
Wingspan	0.9 m (3.0 ft)

SeaSlug.

Mass	Mk.1: 2,080 kg Mk.2: 2,384 kg
Length	Mk.1: 6.0 m Mk.2: 6.1 m
Diameter	Mk.1: 0.42 m That's 16.5 inches Mk.2: 0.41 m
Wingspan	1.44 m

 

[Dilandu]

yeah I was also under the same impression.. still they were trying to sell Egypt a County with horizontal storage. So either what we have both read online is incorrect (possible, very possible), or they had a fix.

Apparently it could be stored horizontally, since box-type launcher was designed and tested. So it would be possible to store Sea Dart in former Sea Slug magazine wihout rebuilding half of the ship. Would still require a modernized launcher, capable of horizontal reload, though.

 

[bobtdwarf]

Apparently it could be stored horizontally, since box-type launcher was designed and tested. So it would be possible to store Sea Dart in former Sea Slug magazine wihout rebuilding half of the ship. Would still require a modernized launcher, capable of horizontal reload, though.

That its just modifying the existing SeaDart launcher... Terrier used very similar to nearly identical launchers for horizontal and vertical launch... you just have to have the arm stop at the correct angle for the missile to cleanly mount the rail.

I DEEEEEEEPLY suspect that SeaDart was intended as a possible SeaSlug replacement in the County's

 

[Dilandu]

That its just modifying the existing SeaDart launcher... Terrier used very similar to nearly identical launchers for horizontal and vertical launch... you just have to have the arm stop at the correct angle for the missile to cleanly mount the rail.

Seems so. The magazine design, on the other hand, would be a bigger headache. The space is too limited for any kind of rotary conveyor system. The best I could suggest is two row of missiles one after another with central trolley that would took the chosen missile from its storage place and move it to loader.

 

[bobtdwarf]

Seems so. The magazine design, on the other hand, would be a bigger headache. The space is too limited for any kind of rotary conveyor system. The best I could suggest is two row of missiles one after another with central trolley that would took the chosen missile from its storage place and move it to loader.

I agree, just using existing with minimal mods to handle the similarly sized and shaped missile. Should work, should be cheap-ish.

 

[Dilandu]

I agree, just using existing with minimal mods to handle the similarly sized and shaped missile. Should work, should be cheap-ish.

Not exactly cheapish - we would still need to remove the whole Seaslug system, develope a new magazine for Sea Dart, install the new magazine and modernized launcher, and Sea Dart fire control. But - it would require only mechanical development (we won't be designing new missile, just a missile storage and handling system)

 

[Dilandu]

So let's summarize the possibilities:

Upgrade a Seaslug GWS by developing new homing (and desirably longer range) missile:

Pros:
+ Would not require major hull or magazine alterations
+ Could use existing fire control system
+ Could implement seeker technology from Sea Dart

Cons:
- Would require developing a radically new model of rather old missile
- The whole system would still be crumblesome and bulky
- Would be less capable than Sea Dart

Replace Seaslug GWS with Sea Dart GWS:

Pros:
+ Significant increase in capabilities
+ Would be based on existing missile, with no alterations required
+ Would provide standartization with newer units

Cons:
- Would require a complete replacement of Seaslug launchers and magazines
- Would require a replacement of fire control system
- Would require a development of completely new, horizontal storage magazine and modernization of launcher for horizontal loading

 

[NOMISYRRUC]

The only references I've got to Type 985 suggest it's a four face PESA system.

We also have something called Trackwell. Which is likely a direct parallel to the multirole Typhon radar.

Now it's theoretically possible for the SSSR effort that resulted in ASWRE C-band 3D radar proposal, which was abandoned for political reasons for the Dutch Type 988 Broomstick. Could become the upgrade to the Countys.

For what it's worth @Hood wrote in Post 63 of the "Rearming the County Class" thread.

As to search radars (I think you asked earlier if any work was done), yes there was research work on new surveillance radars in the late 1960s and some prototyping done by ASWE (I think some have been mentioned on this forum before). But a lot of the work was theoretical stuff (even some novel 360 degree circular arrays) and nothing came of it. I guess Type 988 was syphoning off a lot of money, effort and willpower. It's a shame because I think an SPS-48 type set could have entered service in the 1970s otherwise (you only have to look at Marconi's land-based radars to see what was possible).

And you wrote in Post 66.

ASWRE C-band effort of the early 60’s would resolve this effort. Which weve touched on elsewhere in these scenarios.
Likely by the late 60's to early 70's.
A C-band array was developed
I think there's a Type No, that might be related Type 966? There is a file.....

Edited in additional point.
By using a Mk48 analogue such as the ASWRE C-band 3D radar. The need for the relatively large snd expensive Type 909 TIR can be avoided and a smaller, lighter, and potentially cheaper TIR set used.

Had there been such a effort for the ASWRE C-band and combined with Smaller Seaslug and either one of the alternative twin arm launchers or a single arm development of such...

Then Type 82 gets a little more affordable as would the larger Type 42.

 

[uk 75]

I think the crewing problems together with the poor state of UK industry and government finances probably made upgrading the County class a non starter.
The new T42 provided a more modern missile and gun together with a hangar and Lynx helicopter. Even so, they could not be built and delivered quickly enough.
The failure of Seaslug II doomed the first four ships not to be refitted with the system or receive Exocet.
Otomat on all 8 ships would have been good, together with Lynx.

 

[Dilandu]

Otomat on all 8 ships would have been good, together with Lynx.

Agreed, the Otomat would be much more efficient solution than Exocet.

P.S. I wonder, could Canadian-style telescopic hangar be installed on Counties to simplify helicopter operations and allow to use larger helicopters? The old hangar could be turned into additional storage space or something.

 

[NOMISYRRUC]

Automation needs to be designed in to a ship, its difficult and expensive to refit a ship with it.

For what it's worth the Dutch did it when they refitted their Leanders.

Link to Post 9 of the "Re-arming the Leander class Frigates" thread.

 

[zen]

Another thought about a Seaslug development.

The mkIII is likely a 1950s effort and the potential of application of related technologies from Blue Envoy (originally 200nm but later 150nm range) resulted in the whole thing spiralling off into essentially new missiles (NIGS), new 3D radar (985 NSR etc...) new guidance radar, and new combat management system (ADAWS). Meanwhile a MkII upgrade was developed which doubled effective range to 30nm.
NIGS hit the buffers in the early 60’s.
By which point SIGS had come along. But again, failure to develop SSSR ASWRE C-band 3D radar hampered any upgrade and new build. Type 988 Broomstick proved part of both why Type 82 was cut and why such an upgrade wasn't affordable for the Counties.

Now had a tighter focus been held on a mkIII Seaslug, and here Dilandu is right to suggest the addition of IR seeker for terminal homing. Or the use of polyrod interferometer SARH.
Then with the right improvements in rocket motor, autopilot and Command Guidance, it's possible to get a Seaslug-like missile much greater performance. It's quite reasonable to expect something like 60nm range, maybe more, maybe 90nm. With greater engagement envelope and thus potential against faster and higher targets.

Had ASWRE C-band 3D radar reached production, we'd see this piled on Counties, Type 82, Carriers and Frigates in various scales.

Now that potential has knock on effects, because if you're developing such system, it's applicability for say the Army or Airforce isn't to be ignored.
An ironic twist is a Seaslug MkIV might supplant Thunderbird and even Bloodhound......

In fact had a constrained Seaslug MkIII progressed in the mid-to-late 50's, Bristol's jamming Blue Envoy systems onto Bloodhound (knocked up in the back of taxi) might be rejected.

 

[Dilandu]

Then with the right improvements in rocket motor, autopilot and Command Guidance, it's possible to get a Seaslug-like missile much greater performance. It's quite reasonable to expect something like 60nm range, maybe more, maybe 90nm.

That's a bit too far, I think. The comparable performance with later Terrier's - 30-40 nm - probably could be achieved without altering the missile compatibility with existing launchers.

 

[starviking]

The failure of Seaslug II doomed the first four ships not to be refitted with the system or receive Exocet.

What was the failure of Sea Slug II?