Site Records

Site Name:RAF Saxa Vord ('AXA') CEW R10 ROTOR Radar Station

Shetland Islands
OS Grid Ref: HP629165

Sub Brit site visit 4th June 2004

[Source: Nick Catford & Ian Brown]

In February 1940 instructions were issued by the Director of Signals Development at the Admiralty for construction to began on Admiralty Experimental Station (AES) No. 4 on the island of Unst in the Shetland Islands.

Photo:Panoramic view of RAF Saxa Vord in the 1987
Photo from RAF News

The site selected was on top of Saxa Vord, at 950 feet the highest point on the island. Due to delays caused by the weather and RAF requirements for equipment, the station did not become operational until September 1940. Saxa Vord (the Navy appear to have referred to it as a single word, the RAF as two) was equipped with CDU (Coast Defence U-Boat) radar, the Naval version of CHL, and was tasked with tracking submarines and shipping attempting to break out into the Atlantic. It was also able to plot aircraft and was to play a major part in the destruction of several German aircraft in the area. Saxa Vord closed down in July 1945, having been manned by the RN throughout its operational life.

In 1956 construction of a new radar station, on the same site as that which had been used by the Navy, was begun by the RAF.

The final stage of the ROTOR Programme (Rotor 3) was to provide radar cover for the north and west of the British Isles which were still exposed to attack and to give low and surface level cover over the Atlantic, the absence of which prevented effective action against low flying enemy aircraft. Three new Centimetric Early Warning (CEW) stations were to be built at Saxa Vord, Aird Uig and Faraid Head equipped with Type 80 Mk 2 and Type 13 radars . The new CEW operations buildings were to be above ground and designated R10, similar in internal layout to the underground R1 bunker.

Photo:The R10 Operations Block. The three storey building to the rear housed an Admiralty Experimental Station. It was originally a single storey building,
the other stories being added at a later date
Photo by Nick Catford

ROTOR 3 included five new Chain Home Extra Low (CHEL) stations equipped with Stage 1 radar equipment to enable detection and tracking of low flying aircraft. (Stage 1 could comprise of Type 7 Early Warning [E/W] GCI, Type 14 E/W search radar E/W or FC [CEW station], Type 13 H/F and a Type 15 [mobile Type 7]) The proposed stations were at Kilchiaran, Murlough Bay, Prestatyn, Snaefell and West Myne. These were to be brick built operations blocks, designated R11; the above ground version of an R2 bunker.

Two new GCI stations were also proposed as part of the ROTOR 3 programme, each equipped with a Type 80 radar and R8 prefabricated operations block. One at Ballywooden (Killard Point) in Northern Ireland and the other at Wick on the Scottish east coast.

It was hoped that The ROTOR 3 programme would be complete by 1957 and all technical aspects were classified as 'Super Priority'.

Photo: Type 80 radar at RAF Saxa Vord in 1957/8
Photo by Terry Luxford

A 1956 Works File (Air 2/12064 - 6) lists the radars and equipment that were to be fitted at Saxa Vord. These include Stage 1A (Type 80) radar on the site of the WW2 Chain Home Low operations block with three Type 13 height finders. All evidence of the CHL was cleared away during the construction work.

Originally an R8 operations block was planned for the summit of the hill, close to the modulator building but as there was insufficient room this was dropped in favour of a brick built R10 on the hillside below. Other planned installations included a 'small' VHF transmitter with a 90' mast located at 'Ward of Hardwick' (HP645153); this was to be a modified version of the standard 'small' VHF transmitter building incorporating a GPO radio link. The 'small' VHF receiver with a 90' mast was to be built at 'Southers Field' (HP634153).

Plan of RAF Saxa Vord

As the operations block was to be located 35 metres below the Type 80 modulator building the two sites were to be linked by 200 concrete steps which were later covered over to provide the covered way that is still in use today. There was also to be a Canberra style guardhouse (now demolished) at the entrance to the technical site.

When the installation was completed some changes were made to the 1956 plans and the station was fitted with a Stage 1A (Type 80) radar housed in a modulator building at the summit of Saxa Vord. There was also one Type 13 radar on a Mk VI plinth and one Type 14 radar on a Mk IX plinth.

In the R10 operations block there were six Type 64 consoles, two Type 61 consoles, one 'A' scope, 3 video mapping units and one VHF radio link.

Type 64 console

One major problem did, however, have to be overcome. The erection of the Type 80 was seriously delayed when, in January 1956, the aerial array was blown completely off its mounting and ended up 50 yards downwind. The array of the Type 80 had been tested during the design stage and it had been shown that it would continue to rotate in winds up to 80 miles per hour. In winds exceeding that speed the array would `weather-cock' and thereby survive winds up to 120 mph. However, the radar station holds the unofficial British record for wind speed, which in 1962 was recorded at 177 mph; just before the measuring equipment blew away. This was clearly well in excess of the speeds which the aerials were designed to survive. It was decided in view of such weather conditions that a radome should be built over the aerial array and, with Saxa Vord providing cover of value to NATO, the latter organisation provided the radome, while the RAF, in the form of No. 91 Signals Unit, operated the radar from 1957 onwards.

Photo:The radome at Saxa Vord on a typical Shetland day. The building to the left now occupies the site of the Type 80 modulator building which has been demolished (see picture above). On the far left, behind the white car is the top of the covered way from the operation block on the hillside below.
Photo by Nick Catford

Following the demise of ROTOR the air defence of the UK was reorganized once again. ROTOR gave way to a system of 'Master Radar Stations' (MRS) that provided radar coverage of the UKADR, the United Kingdom Air Defence Region. In the mid 60's MRS's started to give way to the 'Linesman/Mediator' system that was served by radar's from RAF Saxa Vord in the north of the Scottish Shetland islands, RAF Buchan, near Peterhead, Scotland, RAF Boulmer in Northumberland, England, RAF Staxton Wold in Yorkshire, England and RAF Neatishead in Norfolk, England.

The height finding element of the Linesman system, the HF 200 succeeded the American AN/FPS-6 height finder radars used in the ROTOR system. The HF 200's (along with the AN/FPS-6) were also known as 'Nodding Horrors' and they spewed hydraulic oil everywhere. HF 200 Mk3's were located at the three main linesman sites at R.A.F. Boulmer, R.A.F. Staxton Wold and R.A.F. Neatishead while a Mk4 was commissioned at R.A.F Saxa Vord in in 1979.

For further information and pictures of RAF Saxa Vord click here

[Source: Nick Catford & Ian Brown]

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