Thursday, 31 March 2016

RAF Noss Hill - Air Ministry Experimental Station (AMES) No 54


At the beginning of WWII the UKs Chain Home RDF system stretched along the south and east coasts of England and up the east coast of Scotland. However, the most northerly station was at Netherbutton, near Kirkwall,  in Orkney and the equipment there was designed to look primarily to the south-east. In the early part of the war, with all three services having strong operational requirements for this technology, manufacturers of RDF (radar) components had difficulty keeping up with the demand and it was necessary for priorities to be established. Nevertheless, the allocation system had to be flexible to meet new needs. In April 1940 German forces invaded Denmark and Norway leading to the decision to expand radar cover in the Northern Isles.
From the Shetland perspective this meant the immediate formation and dispatch of a radar unit to Unst (No 3 Transportable Radio Unit - http://ahistoryofrafsaxavord.blogspot.co.uk/2013/01/the-first-radar-on-unst.html). It was also decided to build two permanent sites in Shetland, at Noss Hill at the south end of the Shetland Mainland and at Lambaness, in the north of Unst. Both of these sites would become operational as Advance Chain Home (ACH) stations, quicker and simpler to construct than the full Chain Home (CH) stations, whilst work on the more substantial Final CH equipment and structures continued. The site at Lambaness on Unst (RAF Skaw) will be described in later sections, this article will be confined to RAF Noss Hill.

Noss Hill is just south west of the Loch of Spiggie and about 3 miles north-west of the airfield at Sumburgh. The summit of Noss Hill is 367ft  above sea level and, when construction began, there was already an operational Navy radar (AES1), mainly looking for surface plots, at Sumburgh Head. (Left click on pictures to enlarge).

The ACH unit at Noss Hill consisted of a domestic site, two 90ft wooden towers for the Transmitter and Receiver aerials and 3 huts, surrounded by blast walls. The huts were for the diesel generators, transmitter and for the combined receiver/ops room.
In greater detail the ACH Ops/Tech Site looked like this:

The next picture shows the ACH Tech/Ops area from the north-west. The blast walls for the Receiver Hut can be seen in the distance, the power would have been located in the compound centre left and the transmitter hut centre right:

The next photo shows the blast walls which surrounded the Receiver Hut, the footings for the 90ft aerial tower can be seen on the right.

The walls constructed to surround the Transmitter and Receiver are of similar size. Very little, other than sheep droppings, is left inside the blast walls as can be seen from  the following photo, taken where the Transmitter Hut used to stand.

The area which housed the diesel generator is a different shape from the compounds which housed the "T" & "R" Huts, it also has a much larger concrete foundation inside. There are a couple of apertures, which can be seen in the far wall in the next picture - these were possibly used to convey the exhaust fumes from the diesel engines out of the confined space.

Whilst the footings for the "T" & "R" aerial towers were of concrete and steel, the towers themselves were 90ft tall and made of wood. The legs formed a 10ft square at the base and each leg was 5" x 5".
The larger Final Chain Home site took much longer to build and was massive in comparison to the initial ACH unit. The aerial towers dwarfed their earlier cousins and the Transmitter and Receiver/Ops blocks were larger and contained in hardened bunkers.  A hardened Standby Set House, with back-up diesel generators, was also constructed. The labelled extract from Flash Earth shows the main Op/Tech buildings on the CH Site - better descriptions and illustrations will follow.

One of the structures marked on the plan above would not have been there when the CH site took over operations from the ACH site, that containing the IFF equipment - more on this later. I do not have a completion date on the VEB so that may also have been constructed after the rest, once again more later.
CH Transmission
Firstly, I'll take a look at  the transmission side of the Noss Hill CH station. Unfortunately, the bunker which used to house the transmitter equipment is sealed and entry is not possible. However, some details are evident. It's exterior dimensions and shape are the same as the similar building at RAF Skaw - the block measures 72' x 26'. The first two pictures show the outside of the Transmitter Block.


There are some small holes in the wall which appear  to reveal the Transmitter Room at the western end of the block and a very small broken window at the eastern end of the block which reveals  a large chamber, part of which can be seen below:

The radar construction programme in UK was an immense undertaking and, to help speed-up progress, standard plans were drawn up for each type of installation. These plans were adapted to a certain extent on site dependent upon variations in available material and local features. For CH radars there were two main types of plans, those for the earlier east coast stations and those for the later west coast units. The differences were significant with regard to equipment, towers and buildings but rather complex for explanation here. RAF Noss Hill and RAF Skaw surprised me in having features associated with both east and west coast CH Sites. At both sites the layout of the Transmitter Blocks follow the plans for a standard east coast CH site, though with the inaccessibility of the Noss Hill  structure. it's difficult to discover what equipment was inside.
The two Transmitter towers were massive steel structures ABOUT 360 ft tall and could be seen from long distances. At ground level the 4 legs of each tower formed a 64 ft  square. The following picture, taken just after the war and held by the Shetland Museum & Archive Photo Library, shows the site from the north with the Loch of Spiggie in the foreground - the Transmitter towers are the 2 tallest on the left.

CH stations operated on two wave-bands - 10.10 to 13.27 metres and 5.9 to 7.1 metres. Most CH Stations used wavelengths in the longer band. For comparison, the Type 80 search radar, which was introduced in the mid 50's and installed at Saxa Vord,  had a wavelength of about 10 centimetres and the Lightning fighter airborne intercept radar - the AI23B - had a wavelength of about 3 centimetres.
CH Reception
The Receiver Bunker was larger than the Transmitter Bunker and measured 104' x 28'  - it had to house the Operations section too. Once again it was similar to the bunker at Skaw but this time they were both built to a west coast CH design.

Over the years since the war the empty bunker has been used for a number of things, including storage of old furniture. This, combined with access for sheep, has meant the building is in a bit of a mess. At this stage a word of warning to anyone who wishes to enter such places - it will be a lot safer to take a guide who knows the layout and to take decent illumination (a single torch can easily run out of battery life or be dropped). Most of these bunkers had deep conduits in the floors for cabling and there are often old pieces of rusty metal with jagged edges. With the warning over it is time for some photos of the inside of the Receiver block:






The two receiver aerial towers, unlike the steel Transmitter Towers, were made of wood and were only 240ft tall. The bases of these masts can be seen in the next Flash Earth image, the legs of each mast forming a square with sides of about 43'6".

Power
The main Power House was some distance away below the Hill and close to the Loch of Spiggie. The building is now used for agricultural storage:

Three temporary huts (T Hut, R Hut & Generator Hut) were constructed on the Ops/Tech Site, possibly in the period after the main CH equipment had been received and before the large bunkers for the Transmitter, Receiver, and Standby Generator were ready for occupation. All 3 of these huts have been demolished and it is difficult to discover exactly where they were located. The records mention a "second Ops Room" in September 1942 so it is possible that they were in use around this period. The Shetland Museum and Archive Photo Library has a photo of a Noss Hill generator being dismantled in what appears to be a Nissen Hut, which could have been one of the three huts. Alternatively, the Nissen Hut could have been located at a second Domestic Site, to the north of the Main Power House. The picture was taken in the 50's and the person closest to the camera is Bertie Pearson, who worked in the Engine Room of the Earl of Zetland for some years.

 In case of unserviceability or enemy action, a protected Standby Set House was built close to the Transmitter and Receiver Blocks to provide power when required. As can be seen  in the next image it was a substantial structure about the same size as the "T" Block. It is also possible to detect a "ring" around the block - this would have marked the edge of the wartime camouflage. Similar "rings" can be found around the "T" & "R" Blocks.

From the outside the Building looked like this:

All of the military equipment has been removed and the building is now being used to work on local boats.

Identification Friend or Foe (IFF)
The basic principle of IFF was the identification of your own aircraft by using ground equipment, known as an Interrogator, to scan the sky around the radar site. In theory, friendly aircraft illuminated by this interrogator would respond using airborne equipment known as a Transponder. The Interrogator and Transponder used slightly different wavelengths. Aircraft not responding correctly could be assumed to be unfriendly, or at least, worthy of closer inspection. The system was developed to use different pulse lengths etc to carry "coded messages" and could be carried by ships as well. Modern Military systems can be used to determine a wealth of data. Nowadays Air Traffic Control Services also use a more complex form of the early IFF systems, which is more commonly called "Secondary Radar". Transponders in airliners can be used to report aircraft height, to attract attention in case of hijack etc.

An early version of IFF would have been installed at Noss Hill when it became operational but radar developments  were rapid and more advanced systems were being brought in. Changes weren't simple as all users would need to have compatible systems in a short space of time. Agreement had to be reached between the UK and the US if we were to be able to operate in the same airspace and both ground and airborne equipment would need alteration if major updates were implemented. One such upgrade was to IFF Mark III ,which was a major advance, and manufacturers had difficulty meeting the demand for the new equipment
IFF Mark III was installed at Noss Hill  in 1943 and the electrical equipment and building would have been similar to those at AES4, RAF Watsness and RAF Clett, discussed in previous sections. However, the aerial gantry was markedly different. The Chain Home Low/Coastal Defence U Boat sites had an aerial gantry of 28ft - at Noss Hill it was 105ft and was similar to the one in this illustration from the SD0458:

Two other differences were that the gantry base was square rather than cruciform and a substantial set of anchor points had to be made for the tower.

Variable Elevation Beam (VEB)
On my first site visit to the remains of the Noss Hill CH site I was perplexed by a structure of a type I'd not seen before. It appeared to be a small concrete block house or bunker in the centre of the bases of 4 gantry legs. On examining these gantry footings it soon became evident that they are similar to those of an East Coast Receiver tower ie, they formed a 43'6" square and each leg was made from wood measuring 10" x 10" across. It would therefore probably be another 240' wooden tower.

I also took measurements of the block house so that I could produce the sketch plan below:
The next picture shows part of the main chamber:

The puzzle was only solved  with the help of experts who identified the combined structure as the remains of a Variable Elevation Beam height finding system.
One of the major problems early in WWII was determining the height of intruders. In normal conditions skilled operators, if familiar with the particular radar they were using, could usually make  a good estimate of an aircrafts height from the range at which it was detected; ie the further away it was first seen the higher an aircraft was likely to be, the curvature of the earth and the line of sight at the wavelength in use being governing factors. However, once that aircraft was  within radar cover it could climb or descend without this change in altitude being noticed. Frequently fighter aircraft were positioned closely behind an intruder using the 2 dimensional displays available to controllers and operators, only for the height difference to be too great for an intercept to be achieved. One method of assessing an aircrafts height was installed at a small number of Stations, including Ventnor, on the Isle of Wight, and at Noss Hill.  This used what was known as a Variable Elevation Beam (VEB).

In May 1941 it was decided to erect a single VEB at Noss Hill. A series of 7 sets of 8 mechanically linked dipoles were mounted on a 240' wooden receiver tower 25' apart and were tilted in unison through an angle of 15 degrees, a rotating cam near the base of the tower was used to move the dipoles. The system worked on a wavelength of 1½ metres. Three people have been kind enough to send me a picture of the  VEB Tower at Ventnor - it is the one closest to the camera in the following photo and the sets of dipoles can be seen on the left of the structure.

The VEB proved to be fairly accurate but had a number of drawbacks. It was not an "all round looking radar" - its coverage was limited to 60 degrees either side of the direction it had been set to search (line of shoot), so it could only find targets within a 120 degree sector.  The system was also expensive to build, both in materials and manpower. Much smaller height finding systems using centimetric wavelengths (such as the Type 13 - with a 10cm wavelength) were being developed. These used much smaller aerial systems which "nodded" up and down, and could be rotated through 360 degrees. The newer systems made more sense, cheaper to build, more flexible and providing "all round cover". Development work on the VEB was discontinued and it had a short life span. However, some people can't resist wet cement and a lasting legacy from the period can be seen in the main entrance to the Building where a number of initials can be made out. The "W. Mouat" revealed in the next photo is likely to be the name of a local who was employed on the site:
 
Other Structures on the Ops/Tech Site
Air Raid Shelter. Apart from the protected structures housing the Transmitters, Receivers and Standby Power Generators there appears to be just one Air Raid Shelter on the Ops/Tech Site. This is located just north of the VEB site:

The Shelter was obviously visited by Gulls whilst the cement was still wet!

Water Tank. A 10,000 gallon water reservoir was built just south of the Transmitter Block. Water from the Loch of Spiggie would have been filtered, probably through sand, before being chlorinated and stored for use.

Another water tank was raised on a tower close to the Receiver Block, this one holding 1,000 gallons:
 
Water to fill these tanks came from a Pump House by the Loch of Spiggie, approximately ½ mile to the north-east of the site. A windmill would have been needed to pump the water up to the Ops/Tech Site but I haven't found out yet where it was located:

Armoury. Very little remains of the armoury, just a concrete foundation and a small scattering of bricks, close to the Standby Set House:


Gun Emplacements. There were a number of Gun Emplacements and they were of 2 types. Sites for Browning .303 Machine Guns were located on the Ops/Tech Site - these would have been sited for ground defence and for defence against close in, low-flying hostile aircraft. Their maximum effective range was about 1,500 yards. I  have found four of them shown in the Flash Earth Image which follows:

Unlike similar structures at RAF Clett and RAF Watsness, which were built mainly of brick, those at Noss Hill were constructed with cement. The site to the south-west of the Receiver Block is illustrated below:


The other type of gun available had  a greater calibre and a much greater range. Initially two 40mm BOFORs guns were allocated to the Unit but the number may have increased to three or possibly four later in the war. Major Denis Rollo mentions 4 WWII Bofors sites around Noss Hill in his notes, but they were not necessarily all occupied at the same time. These guns, Swedish in design, would have been effective LAA weapons capable  of firing 120 rounds a minute (each high explosive round weighing about 2lb). They were capable of engaging targets as high as 23,000ft. The Flash Earth Image below shows where the 4 Bofors emplacements were and there remain buildings at each of these locations:


The buildings at the 4 sites are similar and their purpose is uncertain. I believe the most likely use of the huts was as shelters for the gun crews who would have needed to be close to their weapons at all times. Ammunition, in steel or wooden cases containing 24 rounds each (often in 6 clips of 4), would have been stored close by and each gun crew would have consisted of 7 to 10 men. The northernmost of these buildings is illustrated below:


Q Buildings. Two "Q Buildings" were constructed, one to the north of the site and one to the west of the Ops/Tech area. Straight tracks led to these structures and the remains of the one to the north of the site can be seen below. As far as I am aware they were designed to be decoy targets in case of enemy attack. The Loch of Spiggie and the Ward of Scousburgh can be seen in the distance beyond the building:


Accommodation/Administration

There were two sites with accommodation. The first, which included the Station administration buildings, was to the south-east of the Ops/Tech Site. The second site was constructed over ½  mile to the NNE of the top of Noss Hill. There is little in the records I have seen which explain the relationship between the 2 sites. I would presume that the first site, closer to the radar equipment, would be used to house the guard force and essential operational/technical personnel. The second site would probably have housed caterers, clerks, MT staff, etc.  For a period, when the Station "hosted" the airmen of RAF Scousburgh (who were awaiting the completion of their own domestic site at Clumlie), the accommodation would have been bursting at the seams.

First Site. Very little of this Site to the south-east of the Ops/Tech Site remains, even the foundations have largely disappeared. The next Flash Earth Image shows the area where the site was located. A few of the visible remains have been labelled.
The diagram below is an amended version of an Air Ministry Works Department (AMWD) Plan of the site. The original must have been drawn off site as some of the locations and buildings were incorrectly identified (2 building 21's for example).
Some of the Site can be seen in this modern photo:
Willie Mainland, who grew up locally, can remember being allowed to sneak through the barbed wire fence surrounding this area by friendly airmen,  so that he could see an occasional film in the cinema.
Second Site. A large accommodation Site for the airmen was built lower down and close to the Loch of Spiggie. It lay at a road junction and was surrounded by a post and wire fence.
I know that the number of people who occupied this camp varied during the war years. I suspect  some of the RAF personnel were moved to the first site, nearer to the radars, sometime after the army guards were removed in June 1942. From November 1942 it would have been packed when the Unit hosted the RAF Scousburgh personnel and yet, in Dec 1943, four of the Barrack Huts and the Recreation Hut were deemed surplus to requirements and put on care and maintenance.  I assume that the Scousburgh Domestic Site at Clumlie had become available.
Very little of this site remains. More modern agricultural structures such as a barn, animal pens and polytunnels occupy the ground. I have labelled a few of the buildings which can still be recognised, on the Flash Earth Image below:
At ground level the area looks like this when viewed from the south-west:
Reserve Site. During the Battle of Britain the German Air Force made a number of attacks on radar sites on the south coast of England. These attacks caused significant disruption to the air defence system and, had they continued, they could well have altered the outcome of the Battle. The need for overlapping radar cover and "back-up" facilities was reinforced. A number of CH stations had reserve sites built, either "Buried Reserves" or "Remote Reserves". Buried Reserves were underground and close to the main site whilst Remote Reserves were usually some distance from the main site. These Reserves would be manned in the event that the main site was put out of action due to damage or communications failure. Construction of a Remote Reserve site was started for RAF Noss Hill, its location was the subject of some controversy and it was never used operationally.
The Reserve was planned from an early date but in the spring of 1941 the Commanding Officer at Noss Hill wrote to higher authority to make it known that he thought the chosen site was unsuitable. The main site already had some problems with higher ground in the vicinity (Fitful Head & Ward of Scousburgh, both around 500 feet higher than Noss Hill). He believed that a site 200' below the summit of Noss Hill was a mistake and another site should be chosen. However, he was over-ruled. At the time the main sector of interest was 100 to 190 degrees - from the east to the south and the scientists on the UK Mainland considered the location to be adequate. In their reply Sigs 4a at the Air Ministry actually said there was no accessible high ground to the north. However, later in the war a GEE site was located on the Ward of Scousburgh at about 860' above sea level and to the north-east of Noss HIll.
The Reserve consisted of three bunkers, a Power House, a Transmitter Block and a Receiver/Operations Block. There were two 120' wooden towers, one each for the transmitter and receiver. It was planned as a complete radar unit  and, with staff, it would have been able to operate independently of the main site. It was located to the south-east of the Ops/Tech Site and close to the higher Admin/Accommodation Site
The location of the various elements of the Reserve can be seen in the next image:
Remote Reserve Power House.
The Remote Reserve had its own Power House:
 
There is nothing left inside (other than more recent sheep droppings), but at one stage it would have housed a generator similar to this one illustrated in the SD4058:
Remote Reserve Receiver Block
The Receiver block is sealed and access is impractical. An external view of the block, with the footings for the 120' tower, can be seen below:
 
The main chamber inside the Receiver Block would have been like this one, which also appears in the SD 4058; however there would have been no WAAFs present: 
Remote Reserve Transmitter Block.
The Transmitter Block is not sealed but I wouldn't recommend access unless you know what you're doing and have sufficient lighting with you - there are a number of deep cable ducts and sharp rusty pieces of metal awaiting the unwary.  The Transmitter Block and the base of a 120' wooden tower appear below, with part of the main CH site on the horizon:
The next 2 pictures, taken inside the Transmitter Block show the Ventilation Plant and the Main Chamber. Note the mount of debris, more recent stored items and some of the cable ducts:

A sketch plan of the Transmitter Block:
In the following pages I intend to outline the main chronology of the site and detail some of the operational events.
RAF Noss Hill - the Early Months
Surveys for Chain Home Sites in Shetland occurred early in 1940 and the location for RAF Noss Hill was probably selected in April or May 1940. Contractors would have been brought in from the UK Mainland and local labour would have been used where possible but the main Contractors, who would have had experience at a number of CH Sites elsewhere, would have been responsible for the more complex tasks. The priority would have been to get the Advance CH Station on the air. In order to ensure arrangements were complete for the arrival of men & equipment, the first Officer to command RAF Noss Hill was required to be at Sumburgh, about 3 miles from the designated site construction site, by 2 Nov 1940. I have one report which names the first CO as Flight Lieutenant WDA Smith. The personnel and their kit (+ 1 rifle per man) were to be assembled at RAF Wilmslow, in Cheshire, by the afternoon of 4 Nov 40 and a ship was supposed to be arranged to carry  the main party and equipment from Aberdeen to Lerwick, sailing by 6 Nov 40. The list of equipment they were to take with them was long and varied, including mundane items, such as cooking utensils, perimeter fencing  and sandbags, plus more complex apparatus like an MB2 Transmitter, a  RM3B Receiver, Vehicles and 2 Lister generators. It is interesting to note that the first operational crew for  RAF Skaw travelled on the same ship from Aberdeen. I believe that they actually arrived in Lerwick on 13 Nov 40 on board the SS Ben-my-Cree, after a  very rough trip from Aberdeen. The Ben -my-Cree, 2,586 GRT, normally operated from the Isle of Man to Liverpool but had been requisitioned at the beginning of the war. In the summer of 1940 she had made 3 trips to Dunkirk to help evacuate Allied troops, before being damaged in a collision with another ship when leaving Folkestone.
Although the would have been civilian contractors on site for some time the airmen would have had a significant role in assembling the ACH equipment, whilst the contractors would have continued with the construction of the CH bunkers and Towers.
Two  Officers were sent by Higher Authority (HQ 70 Group), one to RAF Skaw and the other to Noss Hill, on the 2nd December 1940. They were tasked with the same job - installation duties. The Officer sent to Noss Hill was Pilot Officer GJ Binks and the ACH unit was opened later in December. Although the ACH equipment provided a fully operational radar, the top of Noss Hill and the Domestic Camp were to remain  major construction sites for many months to come. The large blocks and towers for the full Chain Home site had to be completed - those of you who know Shetland can imagine the problems faced with a project of this size, especially in wartime during the winter months and with the material having to be shipped from the Scottish Mainland. From late December 1940 RAF Noss Hill was contributing to the defence of Shetland, Scapa Flow and the rest of the UK.
The Aurora Borealis, the  Northern Lights, caused significant interference to the new radar  on a few days in March 1941 but I have found no records of aircraft activity. In April the command structure for radar stations in Shetland was changed. Up until this time the four Naval Coastal Defence Units (AES 1-4) had been the responsibility of the Navy (albeit with some technical support from the RAF) and the 2 RAF Stations were the responsibility of 70 Wing, based at Bunchrew by Inverness. Under the new arrangements, whilst operational control of the 4 Naval Units remained with the Admiralty, all technical support became the responsibility of the RAFs 71 Wing at Bucksburn, Aberdeen. 71 Wing also assumed total responsibility for Noss Hill and Skaw. With 6 extra Shetland Units to support the Wing decided to send a small technical detachment to Lerwick and to have a centralised equipment store in Shetland.
I have found few records of the early operations of the ACH, the first of any significance being for June 1941. During the month "only 18 Hostile Aircraft were plotted". It  also mentioned that on 11th June the station plotted a Friendly aircraft 180 miles south of the radar - a record for the unit up until this time. There is also a record of a Sgt Peacock and Crew who were sent up to Sumburgh (presumably with an aircraft) to carry out calibration flights for Noss Hill. Skaw and the two Naval CDUs on Fair Isle.
In July 1941 a senior Civilian named Mr Sawyers, who was the representative of Sir Robert Rennick (Chaiman of the RDF Committee), visited Shetland. He made exhaustive enquiries and, after his departure it was hoped " the movement of materials and gear would be speeded up". The note went on to say that progress on the final CH stations at Skaw and Noss Hill had been delayed, in some items for months, by the leisurely procedure followed. On the 11th July Noss Hill, along with a number of other stations, plotted a Hostile for some distance before it was shot down by 2 Hurricanes from Sumburgh. The aircraft was identified as a Junkers JU88. The following JU88 photo comes from: Bundesarchiv, Bild 101I-363-2258-11 / Rompel / CC-BY-SA
August was recorded as a quiet month with only 4 Hostiles plotted. September was also a month with little air activity but the records state that the final CH equipment had been installed, though the towers had yet to be erected. On the 18th & 19th of the month the Northern Lights were seen, though the display was marred by cloud for much of the lime. There was some interference to the Receiver but it was not as bad as that recorded in March.
Another natural phenomenon, an electric storm,  was plotted for 200 miles on 2nd October. The display from the Northern Lights was seen again on the 11th, 22nd, 24th and 31st October, the display on the 31st was particularly brilliant. On these dates  the aurora caused interference which was seen to the west or to the east of the station at different times. The first snow of the winter fell on 29th October. Only two Hostiles were plotted during the month and work on the final CH continued - the installation of the transmitter and receiver arrays commenced. The first half of November brought bad weather with continuous gales, which held up work on the new installation, but in the second half of the month the work progressed well as the weather improved. Once again it was a quiet month with only 4 Hostiles tracked.
There was also bad weather at the start of December. On the 6th a strong gale blew away some sections of a hut which was being dismantled, caused damage to chimneys, windows and the rooves of the Station Headquarters and the Officers' Mess. Although there were some low level attacks against islands north and south of the mainland, the Unit saw little air activity - just one Hostile and 10 unidentified tracks during the month. Over the Christmas period a Concert Party by Station personnel was organised and a Whist Drive, Party & Dance were also held.
1942. January 1942 saw continuous bad weather with high winds and frost, particularly towards the end of the month. Some external pipes burst and some of the internal pipes were frozen for a time. Indoor installation work carried on but outdoor work was only possible on a few days. On the 19th two 40mm BOFORS Guns arrived to augment the defence of the station. Several mines were washed up around the Shetland Mainland and these caused damage to property and a number of injuries. Enemy air activity remained light with only 2 Hostiles and 5 unidentified aircraft plotted.
According to the records, though cold and stormy, the February weather was much better than January and a week long period of almost spring-like weather was enjoyed.   On the 7th an installation party from 71 Wing arrived to carry out work on the new CH equipment and to overhaul the ACH apparatus. Although the weather was reasonable,  work was held up at times due to the late arrival of materials. The number of Hostile aircraft plotted exceeded the  totals of recent months with 13 tracked. Despite some bad weather in March progress with the installation of the final CH site continued to be good.
At 18.00hrs on the 17th April 1942 the Noss Hill final CH station was brought into use, probably from temporary huts as work was still going on in the bunkers. It was the first CH station in 71 Wing to be equipped with an "all round looking" capability - the performance appeared to be most satisfactory and it was a great improvement on the ACH. Although there were some teething problems, the operators and technicians were enthusiastic about the new equipment. Calibration of the radar was postponed, possibly due to a shortage of aircraft and crews. Nineteen Hostiles were tracked during the month but whether this increase can be put down to the improved performance or to a greater number of enemy flights, is not known. The ACH had been the only functioning radar on site for the best part of 15 months. It wasn't closed down but was maintained so that it could act as a back-up should the CH equipment be damaged or become unserviceable (the Remote Reserve was not ready).
The month of May was cold and the weather changeable. An exchange of personnel with the Admiralty Experimental Station, at Grutness near Sumburgh, took place and it was hoped that further exchanges would occur. Thirty-seven Hostiles and 2 Unknown aircraft were plotted and the increase on previous months was attributed to the enhanced performance of the new installation. For some reason the army guard force was withdrawn on 7th June " a most unsatisfactory situation" according to the Units records. A defence course for all personnel, with both classroom and practical lessons, was instigated. The station performance was considered to be reasonable in June, despite problems with the Transmitter switching system which reduced the radar to one "line of shoot", rather than the normal 4. Some interference was also experienced from the south east and it was believed to originate from an enemy source;  however, it did not affect operations seriously. Several good ranges were achieved during the month with one aircraft at 25,000' being plotted out to 195 miles. The better weather in June enabled constuction work to progress well - presumably at the Reserve Site and at the Ops/Tech Site.
The final CH equipment was overhauled and rephased in July, prior to calibration; it was giving excellent results but the calibration did not proceed well because of bad weather. The aircraft used for calibration by 71 Wing included Blenheims. Hornet Moths, Tiger Moths and even Autogiros, though I don't know if any of the Autogiros got as far north as Shetland. If they had been used it must have been very draughty for the crew.
There were numerous visitors to the Station and the Stations's defence was discussed at a couple of conferences, though training (including rifle practice) for unit staff continued. The building of the Remote Reserve was progressing and it was expected that the "apparatus", as the RDF equipment was frequently known, could be installed there in the near future.
In August the calibration of the Station in azimuth (ie bearing rather than elevation) was going well and showing excellent results. Nearly all personnel had completed the defence course of 30 lessons each and the ability to fight fires had greatly improved with the provision of better equipment and the requisite training. Twenty-two Hostiles were plotted during the month and the greatest range recorded was 193 miles.
The azimuth calibration of the Station was completed on the 2nd September and the Air Officer Commanding visited on the 8th. The Unit becames a bit overcrowded as it took on the task of looking after the equipment and personnel of RAF Scousburgh, which was being built just to the north-east of Noss HIll as an Air Ministry 7000 series station (GEE Navigation site). Enemy activity was light, though on the 16th one Hostile was seen for a while flying east at low level to the south of the radar. This aircraft had previously dropped bombs on Fair Isle and, although an intercept was attempted, it escaped without damage being inflicted. On the night of the17th a Coastal Command aircraft was observed to be flying to  & fro around Foula and appeared to  be lost. This was later confirmed by the Filter Office in Lerwick. Because of the accuracy of the plots given, a friendly aircraft was used to guide the lost aircraft to Sumburgh. The radar performed well during the month with the longest range of 175 miles being obtained on a bearing of 200 degrees.
Work on improving the defence of the unit continued into October but construction of some of the positions was held up because of poor weather. Security of the Station was greatly enhanced with the deployment of a section from the Corps of Military Police to patrol and guard the Tech/Ops site. Of the 700 or so tracks plotted during the month only 16 were Hostile - the majority of the others were Coastal Command and Fighters (419 & 151 respectively). As a result of strong winds a number of balloons were tracked. Two test runs were carried out to help in the production of a Vertical Polar Diagram (VPD). VPDs were intended to show the shape of the radar beam/s in a vertical plane and could be used to help estimate the height of an aircraft. A new receiver and console were brought into use and it was thought they provided greater efficiency and accuracy.
There was a significant Operations Record Book entry in November 1942 - "The remote reserve at Noss Hill has finally been abandoned. The many pleas from the technical section about the unsuitable siting of the station have now been answered". The station continued to feed and accommodate the RAF Scousburgh personnel during the month, ration strength approaching 200 for most of the time. The catering and MT sections were particularly stretched by the extra work involved. It was noticed that there was very little friction between the two sets of airmen despite the heavy workload. Two new gun pits were constructed, bringing the total to four. Over 600 tracks were plotted, as usual most of them were aircraft from Coastal Command and the equipment gave a good performance.
December started with a Station Exercise. Some Army personnel strengthened the perimeter fence at the Tech/Ops site, providing increased security. Later in the month the atmosphere changed with abundant festivities over the Christmas period. The Entertainments National Service Association, better known by its acronym ENSA and to some of the troops as "Every Night Something Awful", produced a show, followed a few days later by a Gang show and then a show by the RAF Sumburgh Concert Party. Although the radar equipment performed well, bad weather restricted the number of tracks seen to 402.
1943
January had the heaviest falls of snow in Shetland seen for years.  The only other significant event I have record of is what was described as a "kind of cinema chase". There was a serious break down of an aerial switch and no replacement was immediately available. The only spare to be found was at RAF Skaw and this meant a hurried mission involving service MT, a High Speed Launch and considerable foot-slogging though deep snow to fetch the item. After that it took 14 hours of hard work by 4 Technicians to make the necessary repair.
The theme of bad weather continued into February but, rather than snow, it was severe gales which caused the problems. At 19.50 on the 19th the wind brought down much of the main 240' Receiver Tower and some of the Transmitter arrays. Over 170' of the massive wooden tower was brought down in the dark, narrowly missing the Receiver Block and leaving a stump, just over 65' high, which can be seen in this enlargement from a photo held by the Shetland Museum:
The towers which remained were, the two 360' Transmitter towers on the left, the 240' VEB tower and the remaining 240' Receiver tower.
The Advance CH was activated as a stand-in. On the 20th unit mechanics had managed to rig up the B system Receiver (using the lower part of the tower) on the final CH without reflectors and it outperformed the ACH equipment. The ACH was closed down on the 26th February as the results achieved did not justify keeping it on the air. Of the 302 tracks plotted in the month only 3 were identified as Hostile.
Gales persisted into March and air activity only increased slightly. Despite the damage inflicted on the station in the last month the general radar performance was good. Modifications were made to the Transmitters in the middle of the month which increased their working power output to 21KVA. On the 18th a single dipole was positioned at about 180' up the 240' VEB tower in an attempt to provide range detection to the east and west. This was almost immediately replaced with a pair of crossed dipoles to try to give all round range detection. Results of both attempts proved to be poor when compared to the performance already being received from the  B Receiver system. Five Hostile tracks were plotted in the month including Hostile 246 which was at low level and detected only 9 miles from the Station. Fortunately the track had been detected by other radar stations when it was near Fair Isle. The Hostile was successfully intercepted and shot down approximately 12 miles north-west of Sumburgh.
April proved to be a fairly quiet month. Because of their ineffectiveness the crossed dipoles erected on the VEB Tower in the previous month were no longer used. On the 22nd an unidentified track was intercepted 45 miles east of the station - it turned out to be a Coastal Command aircraft flying at 3,000'. A few days later a good intercept was made on a Balloon in the units radar cover, winds at 60 degrees North can make engineless objects travel at fairly high speeds!
Work continued to improve the Receiver B System during May and the results achieved were satisfactory. Work was also carried out on the Transmitter arrays and it was hoped that this would produce an even better performance. Only one Hostile was detected and it was only seen for a short time before contact was lost with it.
A reorganisation within the RAFs 60 Group in June led to the amalgamation of 70 and 71 Wings, resulting in RAF Noss Hill returning to the control of 70 Wing, as had been the case earlier in the war. I have found no record of any special events involving the station in the period from July to October. This is possibly because they were not recorded or because activities occurred elsewhere; for example, RAF Skaw to the north was quite busy during these months.
Mark III IFF, with a 105'mast, was installed and was commissioned at Noss Hill on 25th November. By the 13th December 1943 the ACH 90' Transmitter and Receiver Towers had been dismantled by the civilian contractors Riley and Neate (the firm was responsible for constructing and removing many CH wooden towers). On 17th December 4 Barrack Blocks and a Recreation Hall on the second Domestic Site, to the NNE of Noss Hill, were handed over to the Air Ministry Works Department (AMWD) to be put on Care & Maintenance. I suspect this surplus of accommodation was caused by the movement of RAF Scousburgh personnel to their own domestic site at Clumlie, just below the Ward of Scousburgh.
1944
In January the ACH Transmitter and Receiver were removed from the site. On 20th February Noss Hill was the first of a number of radar sites to pick up Hostile 556. A good track was established and the Hostile was shot down 50 miles out to sea by a Fighter from Skeabrae in Orkney. The Commander in Chief of the Home Fleet, based at Scapa Flow, congratulated the radar stations involved following the destruction of the Messerschmitt Bf109. It is interesting to note that the records show that the dismantling programme for the RAF Noss Hill Remote Reserve was completed in February. Noss Hill was not alone, the Reserves at numerous other stations were also dismantled at about this period including the ones at Skaw, Schoolhill (south of Aberdeen) and Hillhead (south-west of Fraserburgh). Apart from Noss Hill, which never became operational and was closed early probably because of poor siting, the other closures may have been brought about by a reassessment of the threat, the realisation that the main CH sites were difficult for enemy action to take off air or possibly even because equipment was being gathered for the coming D Day landings and it was needed for redeployment to Europe.
It looks as if the operators had  a quiet time in March but the mechanics were kept busy. Work was carried out on both the Transmitter and the Receiver arrays and on the 21st the IFF frequency was changed from 181 to 171 Mc/s. The only notable occurrence between April and July was the visit of a party of Aerial Erectors who overhauled the CH arrays at both Noss Hill and at Skaw in the hope that their work would reduce the likelihood of major problems in the winter of 44/45.  
In August the main PBX (Private Branch Exchange) had to be closed down due to a shortage of Telephone and W/T Operators and a much smaller exchange was set-up in the Guardroom. The personnel shortages would almost certainly have been caused by the D Day landings and the need for specialists overseas and in the south of England. A further sign of the shifting emphasis of the War came in September when HQ 60 Group decided that the number of twin-mounted Browning Machine Guns on each station could be reduced to one, spare weapons were to be moved to the armouries on Ops/Tech sites. Operationally it was the busiest month so far for the number of aircraft tracks plotted, with over 1,700 individual tracks handled. The record for a single day was also broken on the 21st with 103 aircraft movements seen by the Unit - fortunately the vast majority of the traffic was friendly.
Most of the aircraft observed in September were to the east and south of the Station and it was noted that anti-submarine patrols constituted a large element of this activity. It was also recorded that the amount of Swedish civil air traffic had increased - a total of 1,620 aircraft were plotted during the month.
In the following month Swedish Civil movements continued to increase with as many as 6 plotted at one time on the 27th. It was a very busy month with many friendly bomber tracks reported. A total of 3,288 aircraft were seen, far exceeding the previous monthly record for the Station. The azimuth wiring calibration for the Noss Hill Calculator was completed in October. For its time the Electronic Calculator was a fairly advanced piece of equipment. The use of goniometers to measure angles allowed grid references to be calculated and heights to be found using angles of elevation and ranges. The results appeared as illuminated figures and could be used by operators who were plotting tracks and by those responsible for telling track information to higher authority and to adjacent radar stations. The picture below, from the SD 0458, shows what the equipment looked like :
November was a much quieter month operationally with just 778 aircraft movements, mainly friendly bombers. One important event occurred on the 12th when a raid of Lancaster Bombers from 9 and 617 Squadrons sank the Tirpitz with the famous Barnes Wallis Tallboy bombs at Tromsofjord, Norway. Whilst not directly involved, this would have been a morale booster for station personnel.
 Traffic continued to decline in December with just 519 aircraft plotted, practically all coastal, fighter and civil tracks - about one sixth of Octobers peak. Early in the month 2 unused Lister 15 KVA diesel generators were shipped out to No. 4 Maintenance Unit in Carlisle. This left the Station with four 75KVA Blackstone Diesels which had been performing well. There were numerous festivities arranged over the Christmas period; these included;
A Carol Service in the NAAFI on the 24th, conducted by the Padre from RAF Sumburgh, Sqn Ldr O'Neal
A visit by the Station Band from RAF Sumburgh, also on the 24th
A Concert performed by Station Personnel on the 26th
A Games Night in the NAAFI on the 26th
1945
The weather in January was fairly atrocious with snow, gales and freezing temperatures. The Stations water intake at the Loch of Spiggie became completely blocked by ice and for 2 days there was no running water. The snow and ice interrupted the transportation system and life was particularly unpleasant for a while. Some damage was done to the Transmitters aerial system and it was only by hard outside labour that the unit was kept on the air for much of the month. Coastal and civil traffic accounted for most of the 779 tracks plotted during January. One Bomber Raid of about 50 aircraft, heading north-east towards Norway was seen on the 12th and one Hostile was detected south of the station - it was heading north-east at about 30,000' and finally faded to the radar at a range of 210 miles.
No Hostiles were reported during February but the number of aircraft seen rose to 1,055, but, in the words of the Commanding Officer "there was little of historical interest to report". Movements increased again in March with 1,322 aircraft seen, the majority being coastal and civil and it was noted that there had been a considerable increase in the civilian traffic during the hours of darkness. On the 17th 25 aircraft in groups of 2 and 3 were observed inbound, they were part of a sweep returning from Norway. Amongst them were 12 Beaufighters which were visually identified on their way into Sumburgh.
April saw just one Hostile - H621 which eventually faded 206 miles east of Noss Hill. No action had been taken as the aircraft was originally misidentified as a Friendly reconnaissance mission. It was an eventful month for RAF aircraft, beginning on the 5th when 2 Beaufighters Mk X were picked up 45 miles away. The Mk III IFF equipment indicated one of the planes was in distress and indeed one of them had been damaged during a Norwegian anti-shipping strike and was returning with its port engine damaged. On reaching Sumburgh the pilot was having difficulty controlling the aircraft and, rather than overshoot the runway, he retracted the undercarriage. Although he and the navigator were injured, they both survived.
Then late at night on the 10th a Lancaster was picked up south of Shetland with an unserviceable W/T set. When it eventually landed at Sumburgh it was discovered that the aircrew believed themselves to be in Lincolnshire! On the 22nd a force of 50+ aircraft attacked and sank 2 ships off the Norwegian coast. At 20.22hrs one of these aircraft was picked up 44 miles east of the Station and the Mk III IFF equipment again indicated the aircraft was in distress. It was another Beaufighter Mk X, which also crash landed  at Sumburgh. On the following day 2 more Beaufighters were picked up 50 miles east of the Station with an associated Mk III IFF distress indication. They were escorted to Sumburgh by a Vickers Warwick where one of the aircraft had to make a belly landing.
May 1945 brought the end of the war in Europe and, although 1,160 tracks were recorded there was nothing else of historical significance and it was noted that the equipment had performed well. In June a quarterly overhaul of the equipment was carried out and the only operational incident of significance occurred on the 20th. A track which had been plotted as 30+ aircraft was seen to head north east until it faded at a range of 90 miles. A visual had been obtained when these aircraft took off from Sumburgh, 3 miles south-east of Noss Hill, and the formation actually consisted of 36 Spitfires and 12 Mosquitos - presumably intending to land in Norway. Two specialist crews underwent training to observe a solar eclipse, due in July.
Between the 1st and 16th July solar observations were made with the recording of much statistical data. The highlight was on the 9th, the day of the actual eclipse. The equipment performed well throughout. Normal activity was on a reduced scale with only 236 tracks reported in the month.
Operational closure of RAF Noss Hill took place on 4th August 1945 and the equipment was put on care and maintenance. The 70 Wing Detachment, which had been based in Lerwick, was moved to Noss Hill and Flt Lt E Leigh Worthington (ex Commanding Officer of RAF Noss Hill) became the Detachment Commander. The detachment coordinated the dismantling of, and storage of, equipment from the other Shetland radar units. By 30th September there were 31 Other Ranks and one Officer still at Noss Hill.  On 20th October Flt Lt Worthington was posted back to mainland UK for release and the Detachment was taken over by Flt Lt JE Patterson. Around the end of October and the beginning of November, all items of equipment stored at Noss HIll and all personnel were moved to RAF Scousburgh, leaving Noss Hill with its equipment on care and maintenance and with no active role.
In 1954 the Territorial Army were given the task of demolishing the CH Towers, as can be seen in this sequence of pictures from the Aberdeen Press & Journal published in October 1954.


 
Note 1.
The Royal College of Ancient and Historical Monuments Scotland (Canmore) holds an interesting RAF aerial photo of RAF Noss Hill taken in 1942. Higher resolution copies of the picture can be purchased from the organisation but even the lower resolution copy available on their main site is worth a close look. The photo, along with some more recent images, can be seen by following this link - the picture I refer to is the second one available on the page:
http://canmore.rcahms.gov.uk/en/site/115426/details/noss+hill+chain+home+radar+station/
Note 2. Personnel
Unlike the radar stations on the UK Mainland no servicewomen (WAAFs) were employed on the Shetland sites, though it was not unknown for organisations, such as the NAAFI, to have female staff. The number of servicemen stationed at RAF Noss Hill fluctuated considerable over its life and, for most of the time, it's not easy to give accurate figures. This is because a number of the people there were from attached units and were not included as being on the strength of the Station in most returns. Attachments included soldiers from Light Anti-Aircraft Batteries, possibly Gunners from the RAF Regiment, Airmen from Airfield Construction Squadrons (Mechanical & Electrical Flights) and the personnel from RAF Scousburgh who were waiting for their own Domestic Site to be ready. 
I have been unable to find any figures for the period in which the Station was operating as an Advance Chain Home Unit. I would estimate that the total involved would be in the region of 100. There probably would have been a couple of Officers (Commanding Officer & Adjutant), about 25 RDF (radar) Operators, 12 to 15 Technical Staff,  Guards & Gunners would add in the region of 30 more and the rest would have been cooks, clerks, MT etc.
In April 42 the Final CH became operational and it is likely that there would have been a small increase in staff. In September the Station started to host the personnel from RAF Scousburgh,  awaiting the completion of their own accommodation. By November the official records stated that the number of people having to be fed and housed at Noss Hill approached 200.  By the Autumn of 1944 the strength was about 57 - 1 x RAF Officer, 1 x RCAF Officer, around 45 other ranks + 10 personnel attached from 5154 Sqn (M&E). The attached personnel were possibly responsible for looking after the generators.
By the end of May 45 the numbers were: 1 x RAF Officer, 60 Other Ranks, Attached 5703 M&E Flight - 13 Other Ranks. The last figures for the month of RAF Noss Hills closure - Aug 45 - show there were just 28 RAF personnel with a Sergeant in charge plus 13 Other Ranks from the M&E Flight.
Few names are recorded in the official records; the few I have with approximate dates are appended below:

Flt Lt WDA Smith - Nov 40 (First Commanding Officer)

F/O Parrish - Pre Aug 44

Flt Lt E Leigh Worthington assumed command 3 Aug 44

F/O DE Kennedy 31 Jan 45 - Temp Command

F/O JB Leith 31 Jul 45 - Temp Command

Sgt JM Hunter replaces Flt Lt Worthington (to Lerwick as OC 70 Wing Detachment) - 22 Aug 45

The 70 Wing Detachment soon moved to Noss Hill with Flt Lt Worthington in charge and he was again in charge of Noss Hill

Flt Patterson took over Noss Hill on 20 Oct 45 and Flt Lt Worthington returned to mainland UK for release. On the 31 Oct 45 all personnel at Noss Hill, plus all moveable equipment, was transferred to RAF Scousburgh and Noss Hill was effectively closed down.

Note 3. There are a few more sections on WWII sites in Shetland hear:-

Air Ministry Experimental Station (AMES) 713 – LORAN on Unst
http://ahistoryofrafsaxavord.blogspot.co.uk/2013/06/air-ministry-experimental-station-ames.html
 Acknowledgements:
Willie Mainland
Mike Dean
Bob Jenner
Don Adams - http://www.ventnorradar.co.uk/CH.htm
Major Denis Rollo (via Shetland Museum)
Shetland Museum and Archive Photo Library
Joyce Henderson - South Mainland Community History Group
SD 0458 Photographic Record of Radar Stations (Ground), August 1943
Air 26 - 092 HQ 70 Wg ORB
Air 26 - 094 HQ 70 Wg ORB Appendices
Air 26 - 095 HQ 70 Wg ORB
Air 26 - 100 HQ 71 Wg ORB
AVIA 7 - 311 Noss Hill
CONTENTS LIST