By Geoff Overend
Friend and volunteer at MOSI (Museum of Science and Industry)
By 1941, 42 Chain Home and 52 Chain Home Low stations were in operation
The Metropolitan-Vickers Electrical Company Ltd in Trafford Park made many contributions in the field of science during its lifetime.
Perhaps one of the most important was Metrovicks' pioneering work in the field of Radio Direction Finding (RDF), later to be known as Radar, which commenced in June 1937.
The work eventually led to a network of radar stations across Britain, which was instrumental in helping the RAF win the 1940 Battle of Britain.
In 1935, a number of experiments, under the direction of Robert Watson-Watt, were carried out using radio waves.
Later experiments replaced continuous wave radiation with pulses of radio energy microseconds long which could accurately measure the time taken for an echo to be received back from a target aircraft at ranges up to 17 miles.
By the end of the year, that range had extended to 80 miles.
The success of these tests led to a proposal that a chain of RDF stations should be set up from the Tyne to Southampton at 30 mile intervals - this became known as the Chain Home (CH) system.
Until this point, the experiments had been carried out in utmost secrecy and five sets of equipment had been built, but now another 22 were required.
Radar stations were generally staffed by WAAFs
In early 1938, specifications were issued for both transmitters and receivers and two companies were selected for the commercial production of the systems.
The transmitters were to be made by Metropolitan-Vickers and the receivers by Cossor.
The transmitters were housed in cubicles around 2m³, which housed 1m high valves and the high voltage power supplies to operate and control them.
It being war-time, only two men were entrusted with the full details of the project - Dr J M Dodds at Metrovicks and Mr L A H Bedford at at Cossor.
The companies set to work and by June 1940 - the start of the Battle of Britain - there were 57 operational radar sites in operation, 25 with CH only and 32 more with the additional Chain Home Low (CHL) - a rotating radar beam similar to those now used in Air Traffic Control.
METROVICKS IN WWII
The Trafford Park company produced first Avro Manchester and then Avro Lancaster bombers
Alongside the aircraft, the company also made automatic pilot units and searchlights
Produced one of the early jet engines, the Metrovick F.2 (though it was never used in combat)
Plots of incoming enemy aircraft from adjacent CH stations were passed through a Filter Room and on to Fighter Command Sector Operation Rooms.
There, they were transferred onto large map tables, generally by members of the Women's Auxiliary Air Force who moved the plots as the situation changed.
It was from these plots that Fighter Command controllers were able to direct their fighters by radio towards the enemy aircraft.
The information gave the Hurricanes and Spitfires a vital advantage and helped in Britain win the Battle of Britain.
Many CHL were added during the Battle of Britain and by January 1941, two months after Britain's victory in the air, 42 CH and 52 CHL stations were operational - helping with the war effort beyond those four months of aerial combat in 1940.