Site Name: RAF Sopley ('AVO') R3 GCI ROTOR Station
OS Grid Ref: SZ162978
RSG site visit 23rd May 2000
[Source: Nick Catford]
Following the end of the war the air defence system
was reviewed in the light of experience and a now much reduced budget.
One outcome of this was to nominate one GCI station in each sector
to be an SOC/GCI (Sector Operations Centre) which was in effect the
reserve SOC should the main SOC become non-operational. This upgrading
involved the construction of an extension to the operations room to
accommodate four new cabins with two windows overlooking the reporting
hall, whist the intercept cabins behind the chief controller were
rearranged and enlarged, the RT monitors being relocated in the admin
section. These SOC's remained in use until superceded by the R3's,
R6's and R8's of the rotor system. Sopley became the SOC/GCI for the
Middle Wallop Sector.
Cutaway drawing on an R3 underground GCI technical building
Drawn by Jason Blackiston
The R3 was never intended to survive a direct hit from a nuclear weapon but was designed to withstand a near miss from Russian pattern bombing with 2,200lb armour piercing high explosive bombs (BRAB) dropped from 35,000 feet. It was decided to rebuild the GCI station at Sopley on the opposite side of the road to the happidrome in the field originally occupied by the mobile installation in 1940.
The new station became operational in the summer of
1954 using the callsign 'AVO'; it was fitted with the following radars:
one Type 7 Mk. II, one Type 11 (Mobile) Mk. VII, two Type 13 Mk. VI,
13 Mk. VII, one Type
14 Mk. 8 and one Type 14 Mk. 9. A new domestic camp for 450 personnel
was built near Bransgore village but until this was complete accommodation
was provided until 1952 at RAF Ibsley which had closed as an active
base in 1946.
Photo:The guardhouse gives access to the two level R3 bunker below
Photo by Nick Catford
During 1956 Decca Type 80 Mk. III search radar was installed, replacing the earlier Type 7. The Type 80 was developed in the early 1950's from an experimental design based on the Type 14 Mk VI under the project code name Green Garlic. At this time the two Type 14 radars were dismantled and removed
Almost overnight this new radar made parts of the ROTOR
air defence system redundant. The Type 80 improved the range of the
station considerably with a range of up to 320 miles compared to the
90 mile range of the Type 7; this instantly made some of the earlier
Photo:Sopley Type 80 radar and modulator building
Inside the R3, dramatic changes were also taking place. The large two storey operations room was superseded by a much smaller control room constructed on the top floor at the opposite end of the building. This included a 'well' in the floor for a photographic display unit (PDU) which allowed radar pictures to be projected up into a plotting table from the room below housing a Kelvin Hughes Photographic Projector.
Meanwhile the next frame to be exposed has been following on through the process, so at the end of the next revolution this frame was projected, 15 seconds after its predecessor.
Finally the frame moved on once more where it was projected,
via a mirror, to the underside of the frosted glass plotting table
on the floor above. Meanwhile the next frame to be exposed has been
following on through the process, so at the end of the next revolution
this frame was projected, 15 seconds after its predecessor. As frame
after frame was displayed on the map the plotters in the pit could
place markers on the map to indicate friendly or hostile aircraft.
Room layout at Sopley following the installation of the Kelvin Hughes PDU
Drawn by Nick Catford
With the installation of the Type 80, the Station continued
to operate in the Air Defence Role as a Fighter Control Unit manned
by members of the Royal Auxiliary Air Force and while many stations
closed Sopley was required for the 1958 Plan.
Click here to continue the history of RAF Sopley
[Source: Nick Catford]
Last updated 7th September 2006
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