Sea Slug SAM

No. UK’s GAAP originated in 1944 as anti-kamikaze. As we digested our share of German kit we set up RAE’s Rocket Propulsion Establishment at Westcott. At the Naval Staff Target’s first Project Review January,47 it was given “the highest priority”; RAE tried hard to get it and the entire (to be) GW sector treated as Ordnance – nationalised in R&D and production. RAE’s Morien Morgan advised Ministers not to do such a thing, thus re-run 1920s’ Airships issue. He set about trying to find aeronauts to take an interest. MoS Spec. was issued 3/48 as potential Tri-Service Red Heathen for airfield base and Unit field defence. After much coercion of disinterested Aero industry, in March,49 AWA was given the RN SAM development contract (to be Seaslug I), EE/Luton, the Army’s Unit mobile SAM (to be Thunderbird I) and in April, Bristol, the Army’s airfield fixed SAM (to be RAF Regt.’s Bloodhound I). (Mostly from S.R.Twigge, Early Devt.of GW in UK,Harwood,’93) The industrial risk, of different propulsion/guidance solutions, was spread, in part conforming to MoS’ then-standard presumption that some/most/all UK initiatives would fail.

At the time it was being developed, could Sea Slug have had the same sort of propulsion that Sea Dart did when it was developed – solid booster and ramjet and if so what would that have done to the range of the missile?

The main reason was missile lengh and concerns over missile handling. 20 foot was considered the longest that could easily be handled by the vessels magazines and launcher system, with an in-line booster estimates were that it’d be over 40 feet long, one of the early test weapons in the program that used in-line boosters was 48 feet long if I remember right. The four boosters were inside the main missile wing/fin envelope and so added very little to the missile stowage space requirements or to loading/handling difficulties.

According to RP1 over on Warships1,

Wrap around boosters were used on Sea Slug to “pull” it due to fears that the more conventional booster arrangement would make the missile unstable in the early stages of flight.

As an aside, one of the early Soviet naval SAM projects was to use 4 wrap around boosters at the nose, but this was probably to reduce overall length – that weapon would have been about 15m long!

http://p216.ezboard.com/fwarships1discussionboardsfrm3.showMessage?topicID=5365.topic&index=30

More likely was wrap around boosts came about due to the low power of the British solid rocket motors at the time. Sea Slug used the pull system as it allowed the booster design to dispense with boost fins like those that were fitted to the Bloodhound and Thunderbird, thus making the weapon a lot smaller in all three dimensions. Bloodhound was originally going to be fitted with a Tandem booster based on one of Talos, however it was found that the much smaller tail diameter of the British missile made the chances of design working small, after a lot of XTV 1 and 2 small scale test vehicles jack knifed. After that a design called the overlap was used on later XTV 2,3 and 5s which had a pair of Mayfly boosts mounted each side of the missile in line with the wings (Bloodhound having an X tail configuration at the time). However it was found on the first XTV 4s that reached Mach 2 that the X-tail interacted with the ramjet exhaust and made the round unstable. This was cured with the design that later when into service with allowed the X configuration wrap around boost configuration. Forward mounted boosts were tried on the first Bristol JTV ramjet test vehicles. However they were found to effect the airflow into the ramjet intakes of the JTVand would have also got into the way of the radome of the missile which would have effected the guidance system had they been fitted on Bloodhound 1 (which on had to be locked on to the target before launch).

The Zeus and Spartan also used a motor in a pulling configuration.

According to RP1 over on Warships1,

Wrap around boosters were used on Sea Slug to “pull” it due to fears that the more conventional booster arrangement would make the missile unstable in the early stages of flight.

As an aside, one of the early Soviet naval SAM projects was to use 4 wrap around boosters at the nose, but this was probably to reduce overall length – that weapon would have been about 15m long!

http://p216.ezboard.com/fwarships1discussionboardsfrm3.showMessage?topicID=5365.topic&index=30

Perhaps space constraints on the ships put a limit on the allowable length of the missile?

At the time they probably didn’t have one motor that was big enough to do the job. On the other hand multiple boosters aren’t that uncommon. SA-4, SA-5, Bloodhound, Thunderbird, and others all used them.