The Stage plan

Postwar UK air defence has had a variety of incarnations. Plans such as 1948 ROTOR plan involved a massive investment in bunkers and operations (52 stations were planned) but from the point of view of weapons systems, the Stage Plan is most interesting. This was an integrated air defence system that was intended to develop the radars and missiles in parallel.

In 1949 a series of conferences were held and over the next couple of years the Stage plane took shape. A total of three stages were planned.

Stage 1

Stage 1 was drawn up around requirement OR.1124. This involved the introduction of Surface to Air Guided Weapons (SAGW) to protect the UK's nuclear deterrent, i.e. the V-force and the British Army in the field. To do this they would require a range of 20miles (32km).

The first project to meet OR.1124 was the English Electric Red Shoes SAGW. This mobile rocket propelled missile used the Yellow River pulsed radar (Air Ministry Experimental Station {AMES} Type 83 Fire Control radar, AA No3 Mk9). Red Shoes initially used a liquid fueled rocket engine, but as the Army was not keen on having dangerous rocket fuel around this was soon replaced by a solid rocket motor. Red Shoes was powered by a variety of solid motors included the Albatross, Ratcatcher, Elkhound Wolfhound and Smokey Joe. Red Shoes also used a quartet of Gosling boost rocket motors for launch. On entering service with the Army this became Thunderbird I.






Map showing areas covered by various SAGW stages

A second SAGW was being developed for Stage 1, Red Duster. This was a Bristol Aircraft Company ramjet powered missile for use in fixed installations and would come into service as Bloodhound 1. Red Duster had originally been a research project to assess the performance of ramjet propulsion, with an eye to producing a longer ranged SAGW in the future. Again it used pulsed radar and a quartet of Gosling boosts. Red Duster's early trials were so disappointing that the RAF cancelled its order for an evaluation batch and decided to order Red Shoes to defend its airfields. Bristol Engines made some serious modifications to the ramjets that allowed Red Duster to meet the RAF's needs. Red Duster entered service as Bloodhound I.

Stage 2

Stage 2 to meet OR.1137 was very ambitious and was to extend air defence coverage over the main population centres of the UK, replacing the heavy anti-aircraft guns that had provided such cover since the war. A 200 mile range missile combined with high power radars and a limited anti-ballistic missile capability. The missile was to be capable of command guidance and terminal active homing. The missile, Green Sparkler, was to use a Marconi guidance system that was under development. The US IM-99 Bomarc missile was suggested for Stage 2, but it was thought that its 300+ mile range was excessive and that it would be vulnerable to electronic warfare.

Stage 3 didn't get past the discussion phase and was intended to deal with threats up to 90000ft (27432m) and speeds of Mach 4. Very ambitious.

The Bomarc was not the only missile prone to jamming. The pulsed radars of the Stage 1 SAGW were not only susceptible to ECM but possessed poor low altitude performance.

So, given that Stage 1 had short range, poor ECM resistance and low-level performance plus the realisation that Stage 2 was years away from service, a pair of additional stages were to be added.

The Vulgar Fractions solution - Stage 1 1/2

It was decided to use the recent developments in Continuous Wave (CW) radar and apply that to the Stage 1 SAGW to produce Stage 11/2. This was to be Red Shoes with a CW seeker using AMES Type 86 Indigo Corkscrew radar and was renamed Green Flax. At some point the paperwork was lost and as a security measure the name was changed to Yellow Temple. A further name, VR.725, was applied after the Ministry of Supply was dissolved and applied to a version using the Green Ginger radars. This entered service as Thunderbird II. Given the poor performance of Red Duster, the RAF cancelled its order and ordered Thunderbird II.

Stage 1 3/4

The long-range SAGW requirement would be filled by Stage 1 3/4 to meet OR.1146. This was for a 150-mile range SAGW with mid course update and semi-active terminal homing using CW radar. This became Blue Envoy.

Bristol Guided Weapons' Blue Envoy used a new design of ramjet and a CW radar guidance system probably built around the Orange Toffee radar set and a mid course correction system called Brahms.

The Sandys paper

In 1957 Duncan Sandys presented his infamous Defence White paper. Now, Sandys has been accused of being many things, particularly having an obsession with missiles. If this was the case, why did he cancel the Stage 2 programme and more to the point Stage 1 3/4? Blue Envoy had reached flight test status, and having learned from the Red Duster project, would quite probably have performed as required. However Blue Envoy was also being developed for the Royal Navy and was too big for its ships, but another possibility is that Blue Envoy was to be constructed form stainless steel, and as would later be proved by the Bristol 188, that was a recipe for delay.

The cancellation of Blue Envoy left Bristols with no SAGW work, since Bloodhound I had been a poor performer and Thunderbird II had taken the Stage 1 1/2 role. Bristols decided to use the ramjet technology and CW radar from Blue Envoy and produced Bloodhound II. This had more than double the range of Bloodhound I and Thunderbird II and the RAF opted for Bloodhound II for its air defence.

Perhaps Bloodhound II should have been Stage 1 7/8?

This table shows the comparative performance of UK SAGWs in the late 1950s

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