Site Name: RAF Boulmer ('EZS') GCI R3 ROTOR Radar Station & Control
and Reporting Centre in the UK Air Surveillance and Control System
OS Grid Ref: NU240125
Sub Brit site visit 14th March 2005
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. Boulmer was specifically
built on a new site as part of the Rotor programme but it did
replace an existing WW2 Final GCI (happidrome)
station at Northstead which had been fitted with a Type
7 search radar.
A site chosen for the new Ground
Control Intercept (GCI) station was close to an existing airfield
(RAF Boulmer) which had been returned to agriculture at the end
The station was to have a two level underground operations room designated
as an R3. 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.
The target date for completion of the station was 21st August 1953
and although not complete, the station opened on time with limited capabilities
using an American AN/FPS3
long-range search radar and an AN/TPS10 height finder. The station was
known as 500 Signals Unit under the control of RAF
Acklington and part of 13
drawing of an R3 underground GCI technical building
Drawn by Jason Blackiston
The R3 was complete and the site fully operational in September 1954.
RAF Northstead closed and the personnel moved to the new domestic site
at Boulmer. This was divided into two sites accommodating 'officers
& NCOs' and 'other ranks'. The accommodation was Seco hutting with
a married quarters estate.
This was located a short distance to the east of the R7 bunker with a
small brick built electricity sub station alongside.
|The Type 7 radar at Boulmer was remotely
sited a mile to the east of the technical site on the old airfield
(now Field House Farm) with a ten core coaxial cable linking it
to the R3.
The transmitter, receiver and motor for turning the aerial array
were located underground in a bunker designated as an R7 and known
as a 'well'. Because of the distance from the main site, this
radar required its own IFF and an Mk 10 IFF was mounted on a Type
14 plinth, turntable and cabin. This arrangement of IFF and plinth
was designated Type 79.
Remote VHF transmitter and receiver blocks were also sited at High
Buston and a standby set house (generator) for the technical site
was located at the 'other ranks' domestic site. Mobile reserve sites were
also selected and prepared. Two CEW reserve sites at Embleton Moor and
Christion Bank and an unknown GCI reserve site.
Due to supply and development problems with the introduction of a 'home-grown'
long-range Centimetric Search Radar (Type
80) the station continued to use the American AN/FPS3 long range search
radar and an AN/TPS10 height finder but in January 1956 a Decca Type 80
Mk. III search radar was finally installed and undergoing acceptance trials.
The Type 80 was developed in the early 1950s from an experimental design
based on the Type 14 Mk VI under the project code name Green Garlic; it
replaced the earlier Type 7
||As built the following radars were fitted:
1 Remote Type 7 Mk III above an R7 well with a T79 IFF.
The underground operations room was ready for occupation in 1954 with
the station coming fully on line as RAF Boulmer.
13 MK VII mounted on 9' high concrete plinths.
2 Type 13 Mk VI mounted on 12' high concrete plinths.
Type 14 Mk VIII.
1 Type 14 Mk IX.
1 Type 54 Mk 3 mounted
on a 200' tower for Centimetric early warning (CEW).
1 Type 79 Mk 1.
Almost overnight, this radar made earlier air defence radars (dating
from WW2) mostly 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 equipment
obsolete. Following the installations of the Type 80 the two Type 14
radars were dismantled and removed. The Type 7 was kept in reserve in
case of breakdown or maintenance of the Type 80.
|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 above. This apparatus,
located in the room below was a Kelvin Hughes Photographic Projector;
this comprised equipment that could record the radar image on 35
mm film, develop, fix and
| dry the image and then project it up
on to the plotting table in the control room on the floor above.
The displayed image was only one minute behind real time. The PPI
image from a high intensity cathode ray tube was projected on to
the film through a focusing lens. Each revolution of the radar antenna
took 15 seconds and it took this time to expose the film to a full
revolution. At the end of the sweep, the frame would be moved on
to be developed, whilst the next frame was exposed.
When the frame moved on at the end of the next sweep the image was
fixed, it then moved on again to be dried.
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 had 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.
By December 1956, the main role of the station was a reporting role
for Northern Sector and a standby reporting role for Eastern and Caledonian
Sectors and for Killard Point in Northern Ireland.
modified ROTOR guardhouse is the entrance to the R3 bunker. Click here
to see a picture of the guardhouse before it was modified
Photo by Nick Catford
The station took part in Exercise FORMULATE in 1956. This involved
21 Meteors making a simulated attack from Germany on Northern Sector.
The Type 80 performed well, although it was adversely affected by cloud
cover, but the limited range of the Type 7 proved to be a handicap.
RAF Seaton Snook also
took part in the exercise using Type 7 and Type 13 radars and during
the exercise 432 Light Anti Aircraft regiment defended the base.
for more information and photographs of RAF Boulmer
Last updated 26th May 2006
© 2006 Subterranea Britannica