Site Records

Site Name: RAF Ventnor ('OJC') R1 CEW ROTOR Radar Station

St. Boniface Down
Isle of Wight
OS Grid Ref: SZ568785

Sub Brit site visit 1st October 2004

[Source: Nick Catford]

RAF Ventnor was one of the 20 original Chain Home radar stations authorised in 1937 and the station first became operational in temporary hutting in late 1938. While many Chain Home radar stations around the country closed at the end of the war, RAF Ventnor remained in use and in November 1947 it was one of only 26 operational radar stations in the UK. The Type 24 long range microwave height finder and Types 52 and 53 radars were still in use while the Type 1 Chain Home radar remained on care and maintenance.

Photo:Cutaway drawing of a typical R1 ROTOR bunker
Drawn by Jason Blackiston

The entire station eventually went into care and maintenance. By 1950, the threat of the Atomic bomb had caused a serious rethink in the organisation of air defence and a plan, codenamed ROTOR, was instituted to replace many of the existing stations with new protected underground operations rooms. RAF Ventnor was chosen to participate as part of the first stage of the ROTOR Programme which was itself divided into four phases. Phase 1 was the re-establishment of 28 WW2 Chain Home radar stations. 13 were brought up to a fully operational state while the remaining 15 were brought up to a 'readiness' state. These stations would have required some notice before they were fully operational.

Phase 2 was the construction and installation of 14 new underground Centimetric Early Warning (CEW) and Chain Home Extra Low (CHEL) stations. Phase 3 was the construction and installation of 11 new underground Ground Control Intercept (GCI) stations Phase 4 was the construction of 14 new semi-submerged or above ground GCI stations.

Photo:Aerial view of the ROTOR site in the 1970's. The large building towards the bottom of the picture is the CAA building. Just to the left of it is the ROTOR guardhouse. (Click here for enlargement of the guardhouse). Towards the centre of the picture is the WW2 Chain Home transmitter block and to the left of it the Type 80 modulator building
Photo from NATS

A CEW station was designed to provide the first contact with any attacking force. Its big advantage over Chain Home was its ability to fairly accurately assess height, range and size of an attacking force. The Centimetric Early Warning system needed to be situated at least a 100 feet above sea level and sited relatively close to the coast. The high position of the stations enabled the radars to have an uninterrupted sweep of the coastal approaches of which they protected. Ventnor was therefore an ideal location.

Ventnor (code OJC) was to be one of seven underground CEW radar stations (the others being Portland, Beachy Head, St. Margaret's, Trimingham, Inverbervie & Cold Hesledon). Each of these stations was provided with a heavily protected underground operations room designated R1. Although protected, underground technical buildings were never intended to survive a direct hit from a nuclear weapon but were designed to withstand a near miss from Russian pattern bombing with 2,200lb armour piercing high explosive bombs (BRAB) dropped from 35,000 feet.

Photo:The Type 80 modulator building still standing in 2004 but due for demolition
Photo by Nick Catford

AN/FPS3 Radar
As planned, the station was to be fitted with the following radars, three Type 13 Mk, VI height finders, one Type 14 Mk.VIII and one Type 14 Mk. IX and one American AN/FPS3 and one ANTPS 10. Once development of the centimetric Type 80 radar was complted it was then planned to install this at Ventnor. At this time it was intended that both Type 14's would be removed but one was retained as a back up to the Type 80. The projected completion date for RAF Ventnor was 1.11.1952. The Type 80 was finally handed over to the RAF on 20.3.1956.

The domestic camp and married quarters were located below St. Boniface Down and in order to provide communication between the controllers in the R1 bunker and intercepting aircraft; two VHF/UHF multi-channel radio transmitter and receiver blocks were built across the valley. The receiver was on Stenbury Down and the transmitter, quarter of a mile north on Appuldurcombe Down. These were remotely sited to avoid interference from the radars.

Photo:Type 80 Radar

RAF Ventnor was manned by No. 23 Signals Unit and came under the control of the GCI station, RAF Sopley which, in turn, was administered by the Sector Operations Centre at Box. RAF Ventnor remained operational until at least 1957 but eventually closed and was placed into care and maintenance. The '1958 Plan' states that the station may be required for a different purpose.

Further information and pictures of RAF Ventnor click here

[Source: Nick Catford]

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Last updated 11th December 2004

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