ROTOR

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Entrance bungalow to former ROTOR station at Kelvedon Hatch

ROTOR was a huge and elaborate air defence radar system built by the British Government in the early 1950s to counter possible attack by Soviet bombers. In order to get it operational as quickly as possible, it was initially made up primarily of WWII-era systems, notably the original Chain Home radars for the early warning role, and the AMES Type 7 for plotting and interception control. The system had a network of control stations, mostly built underground, and connected with an extensive telephone and telex network.

Work also began on a new microwave frequency radar to replace Chain Home in the 1957 time-frame. However, an experimental system known as Green Garlic was so successful that it began replacing CH starting in 1954. In service, these proved so accurate that they could replace the Type 7 radars as well, and their greatly improved range meant that far fewer radars would be needed to provide coverage over the entire United Kingdom. This led to the Master Radar Stations that filled both early warning and ground controlled interception roles. The original ROTOR plans for 66 radars was repeatedly reduced, ultimately only requiring half that number of stations.

The AMES Type 80 radars of the ROTOR system were to be replaced by even more powerful systems, the AMES Type 84 and AMES Type 85. However, as the strategic role began to pass from manned bomber aircraft to ballistic missiles, updating the extensive ROTOR network was a low priority. To reduce the budget of a potentially much smaller network, studies on integrating the military radars with civilian air traffic control led to the Linesman/Mediator system of only five primary stations. The original ROTOR was replaced by Linesman in stages, starting in 1967.

A similar expedient system in the United States was the Lashup Radar Network.

Post-war situation[edit]

UK radar operations were wound down late in the war, and by the time the war ended were already largely unused. It was assumed that another war was at least ten years away, and the need for any improvements in the cobbled-together system seemed remote.

Thinking changed dramatically in 1949 with the Soviet test of their first atom bomb. It was known that the Soviets had made exact copies of the B-29 Superfortress as the Tu-4 Bull, and these aircraft had the performance needed to reach the UK with a nuclear payload. Studying the problem, the 1949 Cherry Report suggested that the 170 existing Royal Air Force radar stations be reduced to 66 sites and the electronics extensively upgraded.

Most of the new network would be made up of 28 rebuilt Chain Home systems, while the rest were taken from the existing selection of Chain Home Low, Chain Home Extra Low and the various Ground-controlled interception (GCI) radars that had formerly served special purposes. This was, in part, a stop-gap measure anticipating the availability of the dramatically improved Type 80 Green Garlic radar which would replace the various early warning radars with a single system of much greater performance. Interception guidance would still be handled by existing systems in either case.

All of the radars were to be improved in terms of siting, with the addition of hardened control bunkers to protect the operators from a conventional attack. On the east coast, the coast toward which a Soviet attack would be most likely, the bunkers were underground in the 'R' series (R1, R2, R3 and R4 etc.), while those on the western side of the UK were generally semi-sunken hardened structures ('R6') or above ground 'Secco' type huts (Hartland Point etc.). The R-series bunkers themselves were otherwise similar, featuring 10-foot-thick (3.0 m) concrete walls with all equipment, operations generators and air conditioning located inside.

Additionally, ROTOR re-arranged the existing RAF Fighter Command structure into six "Sector Operational Commands" (SOC) with their own command bunkers (three level 'R4' protected accommodation). Only four of these were built. Additional "Anti-Aircraft Operations Rooms" were built to coordinate the British Army's AA defences in the same overall system. The entire network of bunkers, radars, fighter control and command centres used up 350,000 tons of concrete, 20,000 tons of steel and thousands of miles of telephone and telex connections.

The work was mainly carried out by the Marconi Wireless and Telegraph Company in several phases, called ROTOR 1, ROTOR 2 and ROTOR 3.

Post-ROTOR[edit]

As the anticipated Type 80 "Green Garlic" radar started testing shortly after ROTOR came online, it became clear that it could fill both early warning and interception guidance from a single site. This dramatically decreased the complexity of the ROTOR system, which otherwise required sightings from the early warning radars to be telephoned to the fighter control GCI stations for local plotting. By concentrating all of this complexity at a single site the total number of operators was greatly reduced.

As a result of the introduction of the Type 80, many of the existing ROTOR sites were rationalized into Master Radar Stations (MRS), while the rest were made redundant, some only two years after opening, and all of the AAOR sites were closed. A few of these were re-used for Regional Seats of Government or local authority wartime headquarters. In the mid-1960s the MRSs themselves were replaced with a new system called Linesman/Mediator.

Until the end of the Cold War, many of the sites were retained by the government. They were later sold to private buyers, converted into museums (for example Hack Green) or transferred to the National Air Traffic Control Centre.

List of sites[edit]

Site Name Site Designator Grid Reference Site Purpose
Aird Uig WIU NB 047390 R10 CEW Type 80
Anstruther FAT NO 568808 R3 Type 80
Barnton Quarry MHA NT 203748 R4 SOC Caledonian Sector
Bawburgh WRK TG 165080 R4 SOC Eastern Sector
Bawdsey PKD TM 347388 R3 GCI(E)
Beachy Head HEB TV 590959 R1 CEW Type 80
Bempton RMF TA 192736 R1 CEW
Boulmer EZS NU 240125 R3 GCI Type 80
Box XOB ST 850690 SOC Southern Sector
Buchan GBU NK 113408 R3 GCI Type 80
Calvo CAL NY 144545 R8 GCI
Charmy Down CHA ST 768702 R8 GCI
Chenies HAM TQ 015997 R8 GCI
Cold Hesledon IDW NZ 417468 R1 CEW/CHEL
Comberton COB SO 968461 R8 GCI
Crosslaw HCV NT 880680 R2 CHEL
Danby Beacon NZ 732097 CH
Douglas Wood NO 488415 CH
Drone Hill NT 845665 CH
Drytree SW 732218 CH
Dunkirk TDE TR 076595 CH Type 80
Fairlight GWB TQ 862113 R2 CHEL(A)
Faraid Head RAI NC 389714 R10 CEW Type 80
Folly SM 858195 CH
Foreness WJW TR 385710 R2 CHEL
Gailes FUL NS 327361 R8 GCI Type 80
Goldsborough JEX NZ 830138 R2 CHEL(A)
Hack Green HAK SJ 647483 R6 GCI
Hartland Point HAT SS 237277 R8 GCI
Hayscastle Cross CHX SM 920256 CH Type 80
High Street TM 411720 CH
Hill Head NJ 947616 CH
Holmpton VQJ TA 367225 R3 GCI(B) Type 80
Hope Cove HOP SX 716374 R6 GCI
Hopton TOH TM 540990 R2 CHEL(B)
Inverbervie LGZ NO 841734 R1 CEW
Kelvedon Hatch XSL TQ 561995 R4 SOC Metropolitan Sector
Kilchiaran ECK NR 207616 R11 CHEL
Killard Point IJ 605435 R8 GCI Type 80
Langtoft LAT TF 155129 R6 GCI Type 80
Longley Lane LOA SD 541365 SOC Western Sector
Murlough Bay URB ID 213407 R11 CHEL
Neatishead BWP TG 346184 R3 GCI
Netherbutton BNT HY 464045 CH
Pevensey TQ 644073 CH
Poling TQ 043052 CH
Portland NIB SY 696735 R1 CEW
Prestatyn SYP SJ 079819 R11 CHEL
Ringstead SY 751817 CH
Rye TQ 968232 CH
Sandwich (Ash) YTM TR 303574 R3 GCI Type 80
Saxa Vord AXA HP 629165 R10 CEW Type 80
Scarinish FLY NM 032456 R8 GCI Type 80
School Hill HSL NO 908982 CH
Seaton Snook DYR NZ 519280 R3 GCI Type 80
Sennen SW 376246 CH
Shipton KFY SE 542618 R4 SOC Northern Sector
Skendleby UPI TF 438709 R3 GCI
Snaefell MOI SC 397869 R11 CHEL
Sopley AVO SZ 163977 R3 GCI Type 80
St Annes SAN SD 348303 R8 GCI
St Margarets AGC TR 370451 R1 CEW
St Twynnells TWY SR 944976 R6 GCI Type 80
Staxton Wold TA 023778 CH
Stenigot TF 256827 CH
Stoke Holy Cross TG 257028 CH
Swingate TR 335429 CH
Trelanvean SW 762193 CH
Treleaver TEL SW 766174 R6 GCI(B) Type 80
Trerew RTW SW 812585 CH
Trewan Sands TES SH 322754 R8 GCI
Trimingham QLE TG 290385 R1 CEW Type 80 CHEL
Truleigh Hill SNG TQ 224109 R2 CHEL
Ventnor OJC SZ 565784 CH R1 CEW Type 80
Wartling ZUN TQ 662088 R3 GCI Type 80
West Beckham TG 142389 CH
West Myne ZEM SS 928486 R11 CHEL
West Prawle SX 771374 CH
Wick IKA ND 326537 R8 GCI

The sites today[edit]

RAF Staxton Wold is the only Chain Home site still used as a military radar site but with no remains of the CH station on site after being rebuilt for Linesman/Mediator in 1964. Today it is the home of an RAF TPS 77 RRH (remote radar head).[1]

RAF Boulmer is a working RAF building, which is housed in an ex-"ROTOR" R3 RAF Boulmer ('EZS') GCI R3 ROTOR Radar Station & Control and Reporting Centre in the UK Air Surveillance and Control System.

In terms of current condition, the ROTOR sites vary from demolished to intact.

For example, West Myne[2] in Somerset was the last ROTOR 3 CHEL site. It was completed in 1957 after the introduction of the Type 80 radar and after many ROTOR stations had already closed. The site was within Exmoor National Park and its creation was strenuously opposed by the National Trust who lost no time in obliterating the site immediately after closure.

Many of the buildings have been re-purposed since being active as ROTOR sites. An example is the Bawburgh R4 SOC[3] which was re-purposed as SRHQ4.1 and then RGHQ4.1 to suit the evolving needs of government. The building is intact, but it has been significantly reconfigured since its use as a ROTOR SOC, notably with the addition of an extra floor and the flooring-over of the original R4 operations well.

References[edit]

Further reading[edit]

  • Watching the Skies, Jack Gough, HMSO 1993, ISBN 0117727237
  • Cold War: Building for Nuclear Confrontation 1946-89, Cocroft, Thomas and Barnwell, English Heritage 2003, ISBN 1873592817

External links[edit]