Was "Blue Slug" a real project?

[Maury Markowitz]

I've seen several references to a "Blue Slug", but I cannot find anything in my meagre collection that describes it.

Some online sources claim it was an anti-ship development that lost out to Green Cheese. This seems rather unlikely given that that contest was initially for an unpowered glide bomb that had to be short enough to fit in the Gannet - and I can't imagine any reasonable development of Seaslug that would make that possible.

Others suggest it was an updated Seaslug with the Red Dean seeker. At first glance that seems much more likely, but these claims are far less widespread.

Does anyone have a pointer to some better information on this project, including whether or not it was "real" to the point of a budget?

 

[DWG]

ISTR it's described in British Secret Projects: Hypersonics, Ramjets and Missiles, but I'm several hundred miles from my copy right now. If memory serves, it's Sea Slug in ASuW mode with nuclear warhead.

Given limited warhead production abilities and a nuclear ASuW requirement, it's not impossible to see Green Cheese and Blue Slug as competing with each other for the same production capabilities.

And through the magic of searching the forum for 'Blue Slug': https://www.secretprojects.co.uk/th...d-surface-missiles-1962-70.12273/#post-128403

 

[Dilandu]

This seems rather unlikely given that that contest was initially for an unpowered glide bomb that had to be short enough to fit in the Gannet - and I can't imagine any reasonable development of Seaslug that would make that possible.

Clarification: the contest was, if I recall correctly, about new anti-ship weapons in general. The RN was still hysterical about Sverdlov-class cruisers, and wanted some "Sverdlov-killer" weapon, not particularly caring about what exactly it would be.

 

[CJGibson]

Watch this space.

Chris

 

[SeaslugMk2]

As far as I know (which is relatively little) Blue Slug was an increased-range surface to air/ surface to surface version of Seaslug Mk1 with greater range and higher speed. The surface to surface ability along with the other improvements became Seaslug Mk2.

SRJ

 

[A Tentative Fleet Plan]

See this post elsewhere on the forum:

https://www.secretprojects.co.uk/threads/british-long-range-shipborne-anti-ship-and-surface-missiles-1962-70.12273/#post-128403

The Blue Slug SSM was intended to allow giuided missile destroyers without carrier support to outrange large Soviet cruisers. Designed to use the same equipment as Sea Slug; i.e. same launcher and Type 901 beam-guidance radar, it has been described as being a Sea Slug without the main wings, carrying a Red Angel Warhead and a Red Dean seeker. Blue Slug was cancelled to allow Armstrong Whitworth to concentrate on Sea Slug. Blue Slug would give Sea Slug air-defence destroyers a powerful anti-ship punch and outrange the 6in guns of Soviet Sverdlov-class cruisers, thus avoiding a need to replace a large force of aging British 6in gun cruisers. Sea Slug Mk2W with a limited nuclear anti-ship capability was thought an acceptable compromise.


I think GD.105/55 was the Naval requirement for a nuclear warhead for Blue Slug SSM, with the Red Beard warhead being proposed, but found to be too big.

 

[JFC Fuller]

An abbreviated history of Blue Slug:

By spring 1953 the naval staff was going off the idea of building any further gun cruisers beyond the Tiger class, the cruiser-destroyer and associated 5" MCDP gun would be cancelled later in the year and the cruiser-destroyers previously programmed replaced with a second guided weapon (GW) ship in addition to the already planned first new construction GW ship. At this stage GW ships were to be built to cruiser standards, effectively cruisers would become guided weapons ships and not have large calibre guns. Blue Slug emerged around the same time with a report dated July 1953 outlining a proposal for a naval surface to surface missile. The basic idea was something that could be carried by GW ships that would allow them to drive off an enemy cruiser whilst staying out of gun range, important as GW ships would have limited protection against gunfire.

As the weapon was be used by GW cruisers equipped with Seaslug anyway it made sense to use Seaslug handling and guidance equipment. This had the added, and possibly more important, advantage of reducing the resources required for development which would in turn make it much more likely to be approved. There was a lot of bureaucratic politics with Blue Slug, inside and outside the Navy.

It was April 1954 before consensus started to emerge that the weapon should be subsonic, low-level, and strike the target above the waterline but debate about guidance, speed, trajectory, warhead weight, and striking point against the target continued almost up until cancellation. Industry undertook studies and Armstrong Whitworth submitted a brochure in late 1955 for a subsonic, low-level, weapon with a 1,500lb warhead. GEC appear to have settled on a homing head for guidance, possibly with beam riding for midcourse guidance. By the time the brochure was received Admiralty interest was waning. In late 1954 1SL, Controller, and DNC had ripped up the existing construction programme and reinserted gun armed ships, the GW ships acquired a pair of 6" Mk.26 turrets forward, and the intelligence view of how the Soviets would use Sverdlovs had changed so Blue Slug became a very low priority. The staff requirement was cancelled by mid-1956.

The attached image is an RAE concept for a subsonic, low-altitude (e.g. sea-skimming) anti-ship missile with a 1,500lb warhead.

 

[Dilandu]

An abbreviated history of Blue Slug:

Thank you very much!

 

[Maury Markowitz]

Most excellent, thanks everyone!

 

[zen]

Thank you for sharing JFC Fuller.
We be very grateful.

It does seem a shame this didn't go forward.

 

[Dilandu]

It does seem a shame this didn't go forward.

Well, the idea was... limited. It was within-the-horizon weapon, designed to dealt with enemy gun-armed warships from outside of (efficient) gun range.

Problem is? USSR already worked on much superior anti-ship missiles with over-the-horizon range and autonomous guidance capabilities. The KSCh missile (deployed from 1958) have active radar seeker and could fly over 100 km; thus nullifying the "Blue Slug" standoff potential.

 

[zen]

Well if it gained ARH for terminal flight, then beam rider guidance is to get the weapon close enough.
Even over the horizon.

But ultimately a full ARH only mkII would be needed.

 

[Dilandu]

Well if it gained ARH for terminal flight, then beam rider guidance is to get the weapon close enough.
Even over the horizon.

But ultimately a full ARH only mkII would be needed.

It would require a rather major redesign. Bear in mind, that 1954 "Blue Slug" was likely envisioned as liquid-fuel rocket powered, since "Sea Slug" at this point was supposed to be liquid-fuel powered. So after the decision to switch the "Sea Slug" to solid fuel would be made in 1956, the "Blue Slug" development would face a choice:

* Switch to solid-fuel too - but it would means pretty limited range for sea-skimming missile;
* Remain liquid-fueled - but it would require then an onboard facilities and equipment on ships to work with liquid fuel;

Neither choice was good, frankly.

 

[JFC Fuller]

It would require a rather major redesign. Bear in mind, that 1954 "Blue Slug" was likely envisioned as liquid-fuel rocket powered, since "Sea Slug" at this point was supposed to be liquid-fuel powered. So after the decision to switch the "Sea Slug" to solid fuel would be made in 1956, the "Blue Slug" development would face a choice:

* Switch to solid-fuel too - but it would means pretty limited range for sea-skimming missile;
* Remain liquid-fueled - but it would require then an onboard facilities and equipment on ships to work with liquid fuel;

Neither choice was good, frankly.

The AWA subsonic proposal for Blue Slug, as of 1955, was to use a solid sustainer developing 1,300lb thrust for 100 seconds. Mid-course guidance would be provided by the Type 901 radar. Terminal homing, starting at 4,000 yards from the target, would be undertaken by an X-band seeker based on that for Red Dean, a Q-band seeker was expected to be ready 2 years later.

 

[Dilandu]

The AWA subsonic proposal for Blue Slug, as of 1955, was to use a solid sustainer developing 1,300lb thrust for 100 seconds.

So essentially it would be within the horizon weapon - suitable against gun-only warships, but not against ones with KSCh or P-15.

 

[JFC Fuller]

So essentially it would be within the horizon weapon - suitable against gun-only warships, but not against ones with KSCh or P-15.

KSShch (SS-N-1 Scrubber) and P-15 (SS-N-2 Styx) were both, in practical application, range limited by the radar horizon of their launch ships. Whilst the KSShch could supposedly fly 100km there was no practical means of providing beyond the horizon targeting data, attempts to use a helicopter for this purpose apparently being abandoned, Russian sources give a practical range of 35-40km which is the same as the kinematic range of the P-15 in its initial form. Not until the P-15M was introduced in 1972 did its range extend to 80km.

 

[Dilandu]

KSShch (SS-N-1 Scrubber) and P-15 (SS-N-2 Styx) were both, in practical application, range limited by the radar horizon of their launch ships.

Erm, no. They could not be aimed beyond the horizon by ship's sensors, but they could be launched beyond the horizon using external guidance.

Whilst the KSShch could supposedly fly 100km there was no practical means of providing beyond the horizon targeting data, attempts to use a helicopter for this purpose apparently being abandoned

It's not true. The "Kiprais-56M" fire control system could work with data from any external sources - aerial, shipborne or coastal. The target position, speed and bearing were programmed into fire control calculator, which then calculated the leading point for missile and aimed the launcher. The missile fly to the calculated point by autonomous autopilot, and then activated its radar seeker for terminal guidance.

So it was possible to fire KSCh over the horizon - the target just needed to be observed by someone, so it's movement data could be put into fire control system.

 

[JFC Fuller]

Erm, no. They could not be aimed beyond the horizon by ship's sensors, but they could be launched beyond the horizon using external guidance.

It's not true. The "Kiprais-56M" fire control system could work with data from any external sources - aerial, shipborne or coastal. The target position, speed and bearing were programmed into fire control calculator, which then calculated the leading point for missile and aimed the launcher. The missile fly to the calculated point by autonomous autopilot, and then activated its radar seeker for terminal guidance.

So it was possible to fire KSCh over the horizon - the target just needed to be observed by someone, so it's movement data could be put into fire control system.

This was exactly the point I made, thank you for repeating it, but the piece you didn't mention is that the Soviet's didn't have a survivable asset that could provide that off-board information which meant that the practical range limit on the KSShch was the horizon. Obviously, of the two missiles this only applied to the KSShch as the P-15 was only a 35-40km weapon.

 

[Dilandu]

This was exactly the point I made, thank you for repeating it, but the piece you didn't mention is that the Soviet's didn't have a survivable asset that could provide that off-board information which meant that the practical range limit on the KSShch was the horizon.

What kind of "survivable asset" do you imply? USSR have a capable array of coastal radar-detecting stations, which could be used to pinpoint the position of enemy ships with rather good accuracy. USSR have both land-based and amphibious maritime reconnaisance planes, capable of finding & tracking the enemy ships. And any kind of forward-deployed ship - like Project 31 radar picket destroyer - could be used to provide targeting data for KSCh-armed warship.

The standard way to use KSCh over the horizon was to detect the enemy warships by using radar-detecting stations, and then to pinpoint them with a patrolling recon plane. One pass within radar range would be enough to get target position, speed and bearing. It would be perfectly enough for "Kiprais-56M" to calculate the leading point & fire the missile into it.

 

[zen]

The AWA subsonic proposal for Blue Slug, as of 1955, was to use a solid sustainer developing 1,300lb thrust for 100 seconds. Mid-course guidance would be provided by the Type 901 radar. Terminal homing, starting at 4,000 yards from the target, would be undertaken by an X-band seeker based on that for Red Dean, a Q-band seeker was expected to be ready 2 years later.

This rather sounds like it could be sent over the horizon if the sustainer was able and the electronics of the self guidance could find the target.

 

[Dilandu]

This rather sounds like it could be sent over the horizon if the sustainer was able and the electronics of the self guidance could find the target.

Problem is, that Blue Slug was envisioned to be a sea-skimmer, i.e. low altitude missile. It could not glide much, and required a lot of power to stay airborne. So the only way to produce OTH range would be to drop the sea-skimming demand and make missile semi-ballistic.

 

[JFC Fuller]

What kind of "survivable asset" do you imply? USSR have a capable array of coastal radar-detecting stations, which could be used to pinpoint the position of enemy ships with rather good accuracy. USSR have both land-based and amphibious maritime reconnaisance planes, capable of finding & tracking the enemy ships. And any kind of forward-deployed ship - like Project 31 radar picket destroyer - could be used to provide targeting data for KSCh-armed warship.

The standard way to use KSCh over the horizon was to detect the enemy warships by using radar-detecting stations, and then to pinpoint them with a patrolling recon plane. One pass within radar range would be enough to get target position, speed and bearing. It would be perfectly enough for "Kiprais-56M" to calculate the leading point & fire the missile into it.

Thank you for repeating my point again. KSShch required a platform to get within direct line of sight of the target, the best MPA the Soviets had in the early 1960s was the Beriev Be-6 (even the Be-12 wasn't officially taken into the AVMF inventory until mid-1965). The most likely scenario in which a Blue Slug ship would encounter a KSShch ship would be whilst supporting NATO Carrier Strike Group 2 east of the GIUK line. Whatever the limitations of the Sea Vixen it would have been untroubled the Be-6.

This rather sounds like it could be sent over the horizon if the sustainer was able and the electronics of the self guidance could find the target.

Blue Slug was governed by a desire to minimise development cost as much as possible and to get the weapon into service as soon as possible. This drove the decisions to use the Seaslug radar and launcher/handling equipment. However, at various points those involved did discuss or suggest approaches that would have resulted in a very different and much superior weapon. The Ministry of Supply suggested an inertially guided weapon with an active homing head, this missile would be stored on its own zero-length launcher and not reloaded at sea, conceptually this is very similar to later anti-ship missiles. The other suggestion was the Rolls Royce Soar, which would provide significantly greater range and shows up on Fairey's Project 7. However, OTH engagements require a viable targetting complex....

 

[Dilandu]

Thank you for repeating my point again. KSShch required a platform to get within direct line of sight of the target, the best MPA the Soviets had in the early 1960s was the Beriev Be-6 (even the Be-12 wasn't officially taken into the AVMF inventory until mid-1965).

Thank you for elegangly missing the Il-28, Tu-16, Tu-4 and all the other land-based planes that Soviet Maritime aviation operates. It obviously took you a lot of efforts)

Whatever the limitations of the Sea Vixen it would have been untroubled the Be-6.

Okay) East of GUIK line, you say? Well, then I'd like you to meet 967th ORAP (separate recon air regiment) of Northern Fleet, which was equipped with Il-28R jet recon planes, and since 1956 it started to switch on Tu-16R long-range maritime recon planes. All perfectly capable of providing targeting data for Soviet cruiser/destroyer squadron, steaming to blow apart some unfortunate Royal Navy force (likely already crippled by missile strikes, but let's assume that County survived the ordeal).

Please say your Sea Vixen's that their presence is of absolutely zero value here.

 

[Dilandu]

Setting the puns aside (and may I hope you would do it too?), the Soviet Navy have a reconnaisance/targeting air regiments attached to all major fleets. In mid-1950s, the land-based recon regiments were fully equipped by Il-28R recon bombers - a version of Il-28 with search radar "Kurs", capable of detecting the destroyer-size target from 65+ km (the usual Il-28 have somewhat less capable sighting radar, still able to detect large warships from 40-50 km). With the max range of about 2500 km and max speed of 870 km/h, they are far from "unsurvivable" by mid-1950s means.

And by the time first KSCh-carrying destroyer was officially declared combat-ready in 1958, the maritime recon aviation already started to switch for much more capable Tu-16R, with greater range and speed.

So to put it simple; there were plenty enough of land-based modern jet planes specifically to recon for Soviet Navy. And all of them were perfectly capable of providing KSCh fire control with data, required for over-the-horizon shots. Something as big as County-class would clearly be deemed worthy of a missile (or two), and considering early British SAM limitations agains ASM's...

 

[JFC Fuller]

Thank you for elegangly missing the Il-28, Tu-16, Tu-4 and all the other land-based planes that Soviet Maritime aviation operates. It obviously took you a lot of efforts)


Okay) East of GUIK line, you say? Well, then I'd like you to meet 967th ORAP (separate recon air regiment) of Northern Fleet, which was equipped with Il-28R jet recon planes, and since 1956 it started to switch on Tu-16R long-range maritime recon planes. All perfectly capable of providing targeting data for Soviet cruiser/destroyer squadron, steaming to blow apart some unfortunate Royal Navy force (likely already crippled by missile strikes, but let's assume that County survived the ordeal).

Please say your Sea Vixen's that their presence is of absolutely zero value here.

The Il-28R and Tu-16R were both vulnerable to the Sea Vixen, the British regarded the basic Tu-16 was vulnerable to the Mk.1 Scimitar. The later Tu-16RM working with Tu-16K-10 launching K-10S was a much more formidable opponent but also a generation ahead of the KSShch.

 

[Dilandu]

The Il-28R and Tu-16R were both vulnerable to the Sea Vixen

First of all, Sea Vixen wasn't even around much till 1959. The worst IL-28R would face in late-1950s was Skimitar, and this plane wasn't even radar-equipped; and the Sea Venom wasn't much faster than Il-28 at all.

Secondly, until Sea Vixen FAW.2 with Red Top capability entered service in 1964, the Sea Vixen capabilities against Tu-16R were limited at best. The max speed difference was merely 120 km/h, and Firestreak missiles weren't exactly great weapon also. And trying to go after Tu-16R with cannons could end pretty badly for Sea Vixen (because Tu-16R have cannons too)

So no; while there were some chances that recon plane could be intercepted before it would provide targeting data to warships, it was by no means guaranteed.

P.S. And we didn't even started to consider the possibility of Soviet fighters from coastal airfields getting involved. While specialized Navy fighter units were disbanded in 1960, the Soviet Air Force were still tasked with providing fighter cover for the fleet.

 

[JFC Fuller]

First of all, Sea Vixen wasn't even around much till 1959. The worst IL-28R would face in late-1950s was Skimitar, and this plane wasn't even radar-equipped; and the Sea Venom wasn't much faster than Il-28 at all.

Secondly, until Sea Vixen FAW.2 with Red Top capability entered service in 1964, the Sea Vixen capabilities against Tu-16R were limited at best. The max speed difference was merely 120 km/h, and Firestreak missiles weren't exactly great weapon also. And trying to go after Tu-16R with cannons could end pretty badly for Sea Vixen (because Tu-16R have cannons too)

KSShch "wasn't even around much til 1959" either. The first ship (Project 56EM, Bedovy) commissioned in June 1958, the next three (Project 56M) in December 1958, and the eight Project 57bis ships were commissioned 1960-61.

Sea Vixen with Firestreak, under direction from warships, was adequate against Badgers.

 

[Dilandu]

KSShch "wasn't even around much til 1959" either. The first ship (Project 56EM, Bedovy) commissioned in June 1958, the next three (Project 56M) in December 1958, and the eight Project 57bis ships were commissioned 1960-61.

Yes, and Sea Vixen was firstly deployed on carriers in 1960.

Sea Vixen with Firestreak, under direction from warships, was adequate against Badgers.

Adequate - may be, but still pretty far from your initial thesis about -

Soviet's didn't have a survivable asset that could provide that off-board information

I could agree that Firestreak-armed Vixen have a fair chance to intercept Tu-16, but rather unlikely before it would provide targeting.

 

[JFC Fuller]

Yes, and Sea Vixen was firstly deployed on carriers in 1960.

Adequate - may be, but still pretty far from your initial thesis about -

I could agree that Firestreak-armed Vixen have a fair chance to intercept Tu-16, but rather unlikely before it would provide targeting.

So confirmed, Sea Vixen, KSShch and Tu-16R were contemporaneous and Sea Vixen could intercept Tu-16R. Meanwhile, I'll stick to the reports I have that KSShch was rarely used beyond the horizon of its launch platform.

 

[Dilandu]

So confirmed, Sea Vixen, KSShch and Tu-16R were contemporaneous and Sea Vixen could intercept Tu-16R

Do you admit, that USSR have "survivable asset"? Because if by "survivable" you meant "invulnerable", that's a bit of stretch.

Meanwhile, I'll stick to the reports I have that KSShch was rarely used beyond the horizon of its launch platform.

Since apparently your reports did not mention Tu-16R and Il-28R, their value is a bit dubious. May I inquire about the exact sources?