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As all UK companies were involved in many activities in which they were linked in various ways it is helpful to have a general review of the situation, so John Brown has compiled an introductory piece.

 

If anyone has items of interest please send a note/story to the Editor for inclusion.

 

THE CONTRIBUTION MADE BY THE BRITISH RADIO INDUSTRY DURING THE LEAD-UP TO, AND THROUGHOUT, THE SECOND WORLD WAR

 

METROPOLITAN-VICKERS (METROVIK) LTD - Trafford Park, Manchester.

1932-1935 - Physicist Dr J M Dodds and Engineer Mr J Ludlow, who jointly ran the Valve Laboratory, were involved over this period with the GPO Transmission Group at Daventry, who were evaluating Metrovik’s new continuous evacuated, demountable, water-cooled transmitter valves. In 1933 - early on in their work - a GPO engineer noted that when an aircraft flew past their transmitting centre, it affected the radio reception; however, their work at that time was only to evaluate transmissions in the short wave band (3-30 Mc/s).

 

Back in London, the dominant concern was the perceived German bomber threat, which led to the setting-up of the Committee for the Scientific Survey of Air Defence in November 1934 by Sir Henry Tizard. Shortly after, Robert Watson Watt issued his Memorandum which postulated a solution; it was quickly followed up in February 1935, with the demonstration at Weedon in Northamptonshire. It proved that the fundamental idea was sound; this resulted in the release of Treasury funds for the establishment of the Air Ministry Experimental Station (AMES) on Orfordness in May 1935. Initial progress there was rapid and a prototype Pulse Transmitter was ready two months later.

 

It was foreseen that a larger site would be required, and after a search, Bawdsey Manor was acquired; the move took place during February and March 1935; it became the new AMES. In 1939, the decision was taken that the scientific team should move to Dundee; as a result, the Manor site became RAF Bawdsey - a Station now in its own right.

 

INITIAL ORDERS FOR RDF

May 1936 - Metrovik received an order for 4 Transmitters and 2 Control Desks. May 1936 - A C Cossor received an order for 2 Receiver/Display equipments. Cossor built these equipments based on a design by the Telecommunications Research Establishment (TRE).

February 1937 - Ministry of Aircraft Production set up a network organisation to cover the whole of the RDF project, its implementation, and co-ordination.

 

Apart from Metrovik and Cossor, other companies participating included the following: Dorman-Long - steel suppliers; J. L. Eve Construction Ltd - fabrication of Towers and Masts at each RDF site; and the Radio Transmission Equipment Company - supply of Goniometers. The design of the antenna was a joint project between the AMES and the GPO Group, with Marconi Wireless Telegraph Company Ltd responsible for the provision and erection of the ‘curtain’ antenna arrays.

 

April 1937 - Metrovik - Order placed for 16 Transmitters & 8 Control Desks.

June 1937 - Shipped to Bawdsey, the first 2 Transmitters & 1 Control Desk.

July 1937 - Shipped to Bawdsey, the second 2 Transmitters & 1 Control Desk.

October 1937 - Shipped to Great Bromley Essex, 4 Transmitters & 2 Control Desks.

January 1938 - Shipped to Dunkirk Kent, 4 Transmitters & 2 Control Desks.

February 1938 - A bulk order for 88 Transmitters & 44 Control Desks.

April 1938 - Shipped to Swingate/Dover and Canewdon Essex, antenna, supporting masts and aerial feeder cables.

August 1938 - First 5 RDF Stations - Bawdsey, Great Bromley, Canewdon, Dunkirk, and Swingate/Dover became operational and entered service during the Munich crisis; in full-time operation from September1938.

November 1938 - Metrovik received Transmitter orders for 30 CH (L), and for the Army - 30 Coastal Defence (Mobile Units).

December 1939 - Metrovik received its first orders for 10 Airborne IFF sets.

January 1940 - Further orders for 80 CH (L) and 60 Coastal Defence (Mobile’s)

March 1940 - Metrovik delivered modifications to all the CH stations to change from continuous-wave class B type transmission, to pulse-modulated class C type transmission. Aircraft detection range now increased to at least 150 miles.

October 1940 - Royal Navy approach Metrovik for radio location equipment for ships; ultimately, this led to the Type 271 and Type 272.

 

EKCO (E K COLE LTD) - Southend-on Sea.

The earliest days of radar work - as far as Ekco was concerned - started in March 1938, when TRE (Telecommunications Research Establishment) approached the Technical Director (Mr A W Martin), via Mr E K Cole, to carry out experiments on Radio Location. Ekco had a long-established reputation for innovation, and the quality of its products. This new undertaking was to progress the work that Eddie ‘Taffy’ Bowen had pioneered at Bawdsey.

 

The commission would cover research and development, and thence on to full production of AI (Airborne Interception) radar for the night-fighter force, and ASV (Anti-Surface Vessel) radar for Coastal Command and the Fleet Air Arm. The task had the highest priority.

 

The initial laboratory utilised the entire top floor of the ‘Casino’ building on Canvey Island, made available for the sole use of Ekco, operating under the strictest secrecy conditions; the location was ideal, facing on to passing shipping in the Thames Estuary.

Mid-1939 and onwards - Bletchley Park’s Monitoring Service acquired a number of Ekco Embassy 10 advanced design short-wave receivers (whose performance had been further up-graded) as the first monitors of the German Enigma transmissions. Mr E K Cole in person - not the Ekco Company (for security reasons) - was the point of contact for Commander Ellingworth, the Head of the Monitoring Service.

 

August 1939 - with war imminent, an RAF deputation led by Group Captain Hugh Leedham, Director of Communications Development, called an 08.00 Saturday meeting at Ekco’s Head Office, with Mr Cole and his senior executives. The crucially important development and production of AI and ASV must be carried out at a top secret location; however, it had to be within a 100 miles radius to the west of London.

 

Michael Lipman, Ekco’s specialist in factory planning, was tasked with the conduct of the search - and whilst not being specified - it was implied that the equipment to be produced would be of dimensions not greater than television sets. He was instructed that on approval of the premises of his choosing, they were to be equipped with sufficient machines and tools to enable him to organise production of this unspecified equipment, utilising not more than 200 people. In the event of war, he could recruit a nucleus of staff of not higher than foreman level from the Main Works at Southend. He was to depart on his search mission immediately.

 

After an extensive and comprehensive search, he chose a country house within two miles of Malmesbury in Wiltshire. This was Cowbridge House, an 18^th century house set in 14 acres, close to the banks of the River Avon, which meant that industrial water was available, as was electrical power from its own water-powered generator. The Estate came complete with numerous outbuildings and cottages. He knew straight away that this was the place. The house and the whole Estate were promptly purchased for £6,500 cash. By Christmas 1939, conversation work was completed, while at the same time, making sure that the property retained its appearance of being a country house. When it was operational, packing cases piled outside buildings had to be kept hidden under camouflage netting, and reconnaissance aircraft flew over regularly to check that there were no tell-tale signs of activity.

 

In June 1940, the ‘Top Secret’ research and development laboratory, together with its own workshop, was transferred from Southend to Malmesbury High Street. Here, vacant shops were acquired - and behind painted-out shop windows, conversion work took place to create laboratories and the workshop. This became the WDU (Western Development Unit). These laboratories worked under a cover story of being Ministry of Agriculture and Fisheries offices; thereby - for security reasons - it was kept completely separate and unrelated to Cowbridge House.

 

The WDU Research and Development staff worked ceaselessly with TRE (whose staff included - by this time - the scientist Bernard Lovell), refining the design and performance of AI radar. In July 1940, this resulted in the world’s first successful radar-assisted shoot-down of an enemy aircraft.

 

In parallel with the development and manufacture of night-fighter radars, Ekco also developed and produced ASV radar sets for Coastal Command and the Fleet Air Arm, where they were instrumental in defeating the U-boat threat. With the invention of the cavity magnetron in 1940, a quantum leap forward in performance was made possible, and night-fighters such as the Bristol Beaufighter and the De Havilland Mosquito were soon to rid Britain’s night sky of German bombers.

1941 - AI Mark 4 and ASV Mark 2 radars were in production.

1942 - ‘Centrimetric’ AI Mark 7 and AI Mark 8 radars in production.

1943 - ‘Centrimetric’ ASV Mark 4 in production.

During the war, over 8,500 AI radar sets were manufactured, along with 3,000 ASV radar sets, with production being shared with Pye Radio of Cambridge.

 

Production of H2S equipment was also carried out at Malmesbury.

After the war, production continued at Malmesbury making AI radar sets for fighter aircraft such as the Hawker Hunter; they also made ASV radars for the Fleet Air Arm Fairey Gannets. With the threat posed by the Cold War, in the late 1950’s, EKCO made the tail-warning radar for the RAF’s V-Bomber fleet.

 

September

Footnote: Sir Bernard Lovell’s long association with Ekco Malmesbury is remembered by a road named after him, close to the ‘Cowbridge House’ site which he opened personally at a civic ceremony in November 2009; also invited were some former Ekco employees who had worked there during the Second World War. On the same Estate is another road -‘Lipman Way’ - named as a tribute to Michael Lipman, the Ekco manager who first found and purchased ‘Cowbridge House’ in the dark days of 1939. He was responsible for its conversion to the ‘Top Secret’ factory it became, and managed it throughout the War. His wife ran the Hostels, as well as supervising welfare and the social aspects of the enterprise; a truly remarkable couple.

 

EKCO WORKS - Southend-on Sea.

1939 – Production began of the WS18 mobile HF/VHF/ intercom radio transceiver for inter-tank use by the British Army. This equipment had been designed by Pye Radio, and because of the quantities required, it was also manufactured by Bush Radio and Murphy Radio.

 

May 1940 - At the time of the Dunkirk evacuation, the threat of invasion seemed imminent, and the order was given by the Ministry of Aircraft Production to disperse manufacture away from Southend, which was considered to be in the front line. The Ministry of Aircraft Production had provided a list of potential locations and sites; Ekco chose Aylesbury for its main factory, and nearby Aston Clinton for the Head Office. Aston Clinton House - a former Rothschild property - had been altered some years before to create the ‘Green Park Hotel; it was now taken over as its Administration Centre. Some of the bedrooms were set aside for visiting managers; the remainder for staff use. The former Stable Block was altered to provide development laboratories and a model shop; the conversion work was carried out by Ekco’s Maintenance Department.

 

The colossal task of moving an entire major factory and the Head Office was accomplished in one gigantic effort. During Whitsun 1940, the Ministry diverted a vast fleet of lorries to Southend, and for hours the police closed the A40 to Aylesbury, the London North Circular road, and all four lanes of the Southend Arterial road.

 

The huge ‘Bakelite’ moulding presses - impractical to move - remained at Southend and utilised for munitions work, as did the Lamp Department which reverted to valve manufacture again - but now for radio-location applications. Three further shadow factories were located at Woking for WS19 ‘tank radio’ production; at Preston for lamp production; and at Rutherglen, Lanarkshire, for the manufacture of radio components and transformers.

 

June 1940 - Aylesbury had been contracted to manufacture the T-1154 and R-1155 transmitter/receiver sets. Resulting from numerous technical meetings, the design and development engineers at Aston Clinton carried out re-engineering work on both units for airborne use, before putting them into production. These sets were an original Marconi design that had a steel chassis, whereas the Ekco airborne version had an aluminium chassis for weight-saving reasons, as well as other modifications, either suggested by Ekco or required by the RAF.

 

1941- Production started of the T-1154 and R-1155 transmitter and receiver sets, which became the standard set for Bomber Command for the duration of the war. This equipment was additionally manufactured by EMI (Hayes), Marconi (Chelmsford), and Plessey (Ilford).

 

1942 - The Woking shadow factory developed and manufactured the WS No.46 portable man-pack radio for the commandos.

 

!943- Production returned to the main factory in Southend-on-Sea, with the vast assembly hall now manufacturing Type 19 wireless sets and ‘wiring looms’ for bombers - principally the Avro Lancaster.

Towards the end of the war, with pre-war wirelesses wearing out and more households becoming out of touch as a result, the Southend factory was allowed to first finish off the sets abandoned part-made in 1940, and then to make a cheap unbranded utility set.

 

PYE RADIO - Cambridge

One of the most significant contributions to the war effort can be traced back to early 1939, when Pye engineers were designing their Model 915 television set for the forthcoming ‘RadioOlympia’ exhibition. The set was designed for operation in ‘fringe areas’ (at the limits of coverage from Alexandra Palace - then the sole BBC Television Station). Pye needed an RF amplifier valve with excellent high frequency properties. Through the Mullard Valve Company (Philips’ UK subsidiary), contact was made with the Philips Research Laboratories in the Netherlands, who it was known were developing the EE50 glass-base valve. Pye proposed some modifications to its design, in order to meet its own special requirements. After the initial samples were received, Pye design engineers made some alterations to the valves’ base to improve its performance, and also because of some noticeable distortion effects - resulting from poor screening of the valves’ inner surface -they devised a small red spun-metal jacket to remove them. The Mullard Valve Company manufactured the new red EF50 for Pye. The Model 915 television was displayed at the 1939 ‘RadioOlympia’ exhibition - incorporating their new TRF receiver using five EF50’s - later to become well-known as the ‘Pye Strip’; it was used widely in military radar equipment - both ground and airborne in the Second World War.

 

1940 - Pye stressed to the Government that, although they had a stock of EF50 valves in their Newmarket warehouse provisioned for their pre-war television needs, these would be used up rapidly by the forthcoming demands of radar. By the March, the Government recognised the emergency, and invited Dr Th. P Tromp, General Manager of Philips Electronic Valves to London, where at a secret meeting Watson Watt asked him to send to Britain all the EF50 valves they had, and the tools to make them. Tromp loaded up a Dutch Merchantman (which evaded a German air attack) and arrived at Harwich on 9 May with 25,000 valves and 250,000 valve bases. Hours later, the German army invaded the Netherlands.

 

1939 - WS No.18 the Pye-designed man-pack HF/VHF radio for the British Infantry was manufactured in large quantities.

1940 -The development of the CD and CH (L) radars placed a heavy workload on the Cambridge factory; soon the order for CHL stations rose to 40, of which 25 were to be mobile. Pye undertook to provide the receiver rack and cathode ray tubes, with the ‘Pye Strip’ fitted into a receiver designed by TRE. The mobile CHL was mounted on two trucks for which Pye made the antennae out of chicken wire, and also designed the turntables and steering gear.

Summer 1940 - The Ministry of Supply placed orders - on the Army’s behalf - for another 120 CH (L) stations; part of this order was carried out by Invicta, a subsidiary of Pye.

1941 - WS No.19 set. Designed and manufactured by Pye; it was also manufactured by Bush Radio, Ekco, and Murphy, and abroad in North America and Canada.

1942- WS No.22 set. Designed and manufactured by Pye.

!943 - Radio Link Sounding Range Mark 2, and Communications Rx. Type PTR.

1944 - Communications receiver Type PCR, and WS 10 microwave radio relay station (transportable mounted on a wheeled trailer).

 

COSSOR – Highbury Grove, London

March 1936 - Mr L H Bedford, Chief Research Engineer had a visit from Mr Watson Watt for confidential briefing discussions as to the requirements of RDF. Soon after the Victorian house at the top of the drive at Cossor’s was discreetly converted to a laboratory, where a highly specialised VHF receiver was developed by a team working under L H Bedford and O S Puckle (later in his career, he became well-known for his classic book on time-base design).

 

May 1936 - Cossor’s received an initial order for 2 receiver/display equipments. Note: for security reasons - at the time - there was no knowledge by Cossor of Metrovicks involvement in the RDF project; co-ordination was conducted by AMES Bawdsey.

!937 and onwards - Quantity production of Receiver/Display equipments for CH, CH (L), and CD radar installations.

1938 - In co-operation with the Army Cell at Bawdsey, they begin development/production of the receiver for GL1, the first heavy anti-aircraft Gun Laying Radar.

 

Sept. 1939 - Entire factory concentrates on war production, and also becomes involved in airborne IFF radar development.

1940 - Becomes engaged in munitions work, producing electrically-operated fuse assemblies fitted inside anti-aircraft shells. Shadow factory opened in Wren Mill, Chadderton, near Oldham.

1941- Developing GEE airborne radio location equipment, as well as ground and sea-based communications equipment.

1943 – Moves its valve and CRT business to a new wholly-owned subsidiary -Electronic Tubes Ltd (ETEL) based in High Wycombe.

1945 – Secondary radar for ATC now becomes a key area of development for the Company.

 

GENERAL ELECTRIC COMPANY LTD – GEC – Wembley and Coventry

The aircraft transceivers were developed at the Hirst Research Centre at Wembley, and manufactured at the Telephone Works at Coventry.

1936 - Supplied the TR9 (an HF transceiver) for the Hurricane, and for the early Spitfire’s.

June 1939 - TR 1133G a VHF transceiver replaced the TRG in both aircraft.

1940 - TR 1143, an improved VHF transceiver, replaced the TR 1133G.

!940 - The Company was entrusted to further develop the cavity magnetron (from the one originated at Birmingham University). It subsequently went into quantity production.

 

ELECTRICAL & MUSICAL INDUSTRIES (EMI) Hayes, Middlesex.

1935/36 - Supply of sound locators - when these were still being evaluated as a possible contender for early warning of aircraft.

1939 - There existed some initial reticence to engage the Company fully in advanced radar work (because of security reservations) as the research staff members included some foreign scientists and engineers. Therefore, the first radar-related work was limited to a remedial task to existing equipment. By 1941, the Company was now at the centre of the development of several noted radars, including H2S; the former reservations had been resolved.

 

1941 - Quantity production of the T1154 and R1155 transceivers begins.

July 1942 - The brilliant electronic engineer - Alan Blumlein - was a member of the team carrying out flight trials of H2S in a Halifax bomber aircraft when it crashed. Sadly, he was among those killed. The important work was able to be continued without a break, as all of the design and flight trial results had been well documented.

February 1943 - First systems enter service - H2S Mk1 & H2S Mk2; six months later H2S Mk 3 (X-Band at 3cm - 10 GHz) enters service.

 

MARCONI WIRELESS TELEGRAPH COMPANY - Chelmsford, Essex.

!936 - Initial design of the transmitter ‘curtain’ antenna arrays for CH.

1937 onwards - Production and installation of the ‘curtain’ antenna arrays at each of the East and South Coast CH sites; these were followed by those sites on the West Coast.

 

1936/7 - Baddow began production of an initial batch of Stabilovolt valves, from drawings made available by the Marconi Osram Valve Co; however, having struggled with this task to achieve the target batch number, it was passed on to New Street for quantity production, and thence on to the new Valve Factory in Waterhouse Lane, where vast numbers were manufactured over the war years. Quartz crystal oscillators had always been an important item; the production of which required highly skilled operatives. The demands of war-time applications continued to place an enormous load on the New Street Works.

 

1939 - From the time of the ‘Declaration of War’, the Company was tasked with a series of ‘crash’ production programmes involving their SWB8 HF transmitters and associated communications equipment, but now had also to be installed in motor coaches. Two other major programmes were the manufacture of the T1154 and R1155 transceivers for Bomber Command, flying boats, reconnaissance aircraft, air-sea rescue launches, and also the production of direction-finding equipment. Traditionally, the Royal Navy had always been a major user of Marconi equipment: its orders from now on began to include radar systems.

A further major endeavour was the building of a ‘shadow’ Daventry, in Dorset - as back-up for the overseas broadcasting network; it was followed by a similar station in Yorkshire as a further measure, in the event of possible disruptive enemy action.

April 1940 - Air Ministry took over part of the former Baddow Research Laboratories absorbing the Propagation Group - and soon after - the Instrument Group, to work in conjunction with each other.

May 1941 - The remainder of the Baddow Laboratories came under the control of the Admiralty, to work directly with the Admiralty Signal Establishment.

 

Marconi-Ekco Instruments Ltd had been a joint partnership Company since 1936, for the design and manufacture of a wide range of test equipment in Chelmsford and Southend. In 1939, large Ministry contracts were placed with the Company for all types of test gear; extra manufacturing capacity was obtained by leasing two factories in St Albans and High Wycombe.

In late 1941, Marconi dissolved the partnership - giving as its reason - the complications of dual-control operation in war-time. It was renamed Marconi Instruments Ltd, and became a wholly-owned subsidiary of Marconi Wireless Telegraph Company.

May 1942 – Production of the cavity magnetron began in a new building at Waterhouse Lane, Chelmsford. In due course, several hundred were being made per month, thereby providing a second source of supply to those being manufactured by GEC.

October 1942- Production of the ‘Supersonic Buoy’, designed and developed in Chelmsford (to an Admiralty requirement), and now under-going sea trials. They were first used in the invasion of Sicily for the guidance of transport and beach-landing craft, and later in the D-Day operation. (Editors note - see article below for further information on the buoys) October 1944 - Project ‘Bagful’, was an airborne equipment to intercept and record the frequency, and approximate positions, of enemy radar stations. Designed, developed, and manufactured by Marconi’s - from research data supplied by TRE. The equipment went into large-scale operation a considerable while before D-Day so that, by the time the invasion took place, an extensive dossier had been compiled.

 

PLESSEY COMPANY - Ilford, Essex

1940 - The Plessey factory at Vicarage Lane, Ilford - because of its location - was an early target to be heavily bombed in both the September and October. This led to the decision to convert the twin tunnels - built pre-war as the planned extension of the London Underground Central Line (but not fully completed) - into a munitions factory. It was 5 miles long, with access points to the surface at Wanstead, Redbridge, and Gants Hill; the escalators were available for use at the beginning and end of each shift. The factory area amounted to 300,000 of square footage. An 18”gauge miniature railway was installed to facilitate the movement of employees and materials around, as well as for the completed parts and equipments. By February 1942, it was fully occupied and working two 12 hour, day and night shifts; each shift with 2,000 employees.

 

The products manufactured, ranged from aircraft parts, shell & bomb cases, and radio equipment. The latter category included T.1154 & R.1155 transceivers; B7/RL66, B71/RL66; and RL7 & RL 135 intercept receivers. Additionally, they manufactured a very special cathode ray tube that was used in the FH4, to aid the detection of U-Boats.

1941 - A new factory was built in Swindon, and shadow factories in Walthamstow, and Cardiff.

1940 - The small research & development activity was moved to Towcester. Note: up until this time, the Company had principally been a bulk manufacturer of other firm’s products.

1945 - The underground factory was closed and the manufacturing equipment taken out; furthermore, 12,000 tons of concrete - which had been the base of the floor and foundations for the heavy machine tools - had to be removed, before it could be returned to London Transport. When this had been achieved, the extension building work was re-started; the Central Line - through to Gants Hill - opened in 1947.

_______________________________________________

By the end of the War, the Radio Industry had provided everything that was asked of it – and more – in support of the Armed Forces. Its workforce had performed miracles – in often dangerous circumstances and conditions – and had manufactured an enormous range of equipment.

 

On 31^st of August, 1945 the Radio Industry Council held a lunch at Claridges – the guest speaker was Sir Stafford Cripps who, for some of the war period, had been the Minister of Aircraft Production – the industry’s master. He had been invited now as the recently appointed President of the Board of Trade – once again their influencer.

 

He said the following in tribute to the Radio Industry - which is but a short extract from a much longer survey of the role that the individual companies played, notably in radar and communications.

‘’.... the other great partner in this team-work of research and development, the scientists in the laboratories of the industrial firms, who by their ingenuity and resourcefulness, first turned the rough models and even in some cases the ideas, of the Government scientists into the devices which could be quickly and economically produced in the factories, and which in the exacting conditions of military service, were capable of giving good and continuing performance.’’

 

______________________________________________________ Additional References

Setmakers by Keith Geddes & Gordon Bussey. Published by The British & Electronic Equipment Manufacturers Association (BREMA) 1991.

EKCO Sounds by Chris Poole & Peter C. Brown. Published by Estuary Publishing 2002 .

Marconi – A Wartime Record. Published by Chatto & Windus 1946.

The History of The Marconi Company by W J Baker. Published by Methuen & Co. 1970.

Radio Man by Mark Frankland. Published by the IEE 2002.

 

Editor's Contribution

As well as standard activities the Company was also involved in other excentric activities illustrated by the following item:

 

An editorial in a publication on the occasion of the celebration of the D-Day seaborne invasion, said that “Operation Neptune’, included a rendezvous area off the Isle of Wight - 'Piccadilly Circus' - from where the task groups would sail the channels cleared of minefields. These needed accurate marking, with the entrances to Juno Beach being lit by LV72 and another vessel.”

 

This statement triggered a recollection of an associated technology, namely the supersonic buoys designed by Marconi. These were deployed by the Navy, initially during the Battle of the Mediterranean as radio underwater light-houses for submarines navigating in enemy-mined waters, Eventually on D-Day they acted as guides for surface ships through the minefields in French coastal waters. The story of this is included in “Marconi 1939–1945 A WAR RECORD” by George Godwin, commissioned by the then Chairman Admiral H.W. Grant.

 

THE SUPERSONIC BUOY

Frequently it happened during the War that scientific work was entrusted to the Company by the Admiralty without any information as to the object of it. Thus, on many occasions the scientific and technical side were engaged on projects on terms somewhat similar to those upon which subscribers to a certain South Sea Bubble Company were invited to part with their money: “For a great project, nobody to know what.” The three members of the scientific staff who travelled at the invitation of the Admiralty to a secret laboratory one day in January, 1942, found themselves in that position.

They were asked to consider the possibility of a submarine buoy which would radiate supersonic signals, with a range of four to five miles, which would be sufficient for bearings to be taken on, but would also be incapable of being picked up by the enemy hydrophone equipment. Further, this projected buoy was to be so devised that the enemy would be unable to fish it up if laid in his waters; against which contingency and the possibility of the buoy breaking loose from its moorings, it was to be fitted with a hara-kiri device for blowing itself up. Next, the buoy was to be so mechanised that it would transmit only at set times, and it was to be capable of radiating different pulsing rates to prevent identification by the enemy. And, last, the buoy was to be devised to have a running life of three months, and to be provided with a clock which would keep time to within half an hour in that period, and was to transmit every one or two hours, day and night, but for only fourteen days in the twenty-eight.

 

A WRANGLER’S HEADACHE

The supersonic buoy, as thus presented, looked very much like a Senior Wrangler’s headache. So that it was not very surprising that when the first model had been completed, it proved itself to be a “bad buoy”’ when dropped overboard from a naval craft in Barnstaple Bay.Three test buoys had been laid and anchored on the sea-bed. Then, three days later, when they were recovered, one cable came up without its buoy. A depth charge was therefore dropped on the missing buoy which was washed up three months later on the foreshore, an object of public suspicion and of police activity.

Further tests were carried out by the Company’s scientists in May, off Felixstowe, from a minesweeper, primarily to determine the buoy’s range, the suitability of the signals, and its general reliability. It was then established that the range was upwards of four to five miles when the receiving vessel was hove to, and about three miles when steaming at ten knots.Several details had to be attended to assure that the buoy would not drag its moorings in a tideway, or be tilted from the perpendicular, so that the horizontal radiation would not be impaired. These difficulties were overcome by the bridal tackle, and the buoy was put into production, sea-trials taking place 1st-3rd October, 1942.

 

A GREAT PROJECT.

What, then, were these buoys intended for and what might be the connection between them and the Battle of the Mediterranean? To-day, it is permissible to answer both questions.The purpose of these truly-remarkable buoys was to act as radio underwater light-houses for submarines navigating in enemy-mined waters. They were laid by surface craft in information from high-flying aircraft for whom the channel through the mine-fields was rendered visible by height. The buoys were first used in the invasion of Sicily to guide transport and beach-landing craft on to the beaches, such craft being equipped with wireless to put out signals. The buoys had been developed by the Company (it had a secret department where naval models were made and tested) to the point where a model was evolved that could be fired from the torpedo tubes of a submarine at periscope depth. And this model, the Mark II, was used and proved very successful, not only for the Sicily landings, but at Anzio also. The later use of the buoy may well have had its origin in a makeshift device which was used during the preparations for the landings on the beaches of Sicily. There the buoys were needed to guide in the radio-equipped landing craft to their appointed positions on the beaches. The difficulty arose of getting the buoys laid without arousing the suspicions of a very nervous enemy. The usual method of laying from motor-launches was out of the question, it was therefore decided to use submarines. The supersonic buoys were lashed to the submarine casings and taken in at periscope depth to the shallow waters. There the submarines surfaced, unlashed and laid the buoys and submerged, all by the bright lights of the Mediterranean moon.

 

Another job done by the supersonic buoys was at the time of the midget submarine warfare in the English Channel and on the North Sea routes. They were then used to mark sunken wrecks and thus to prevent submarine craft wasting time and depth-charges on wrecks picked up on their Asdic gear. But perhaps the most important work performed by these remarkable scientific buoys was that done on D-Day.

 

BUOY-GUIDED SHIPS

It will be remembered that the date set for the Invasion was one based on meteorological records extending over a great many years as that when good conditions might be anticipated with confidence. For days before 6th June, however, the weather conditions continued incontinently bad. It was in the awkward, choppy sea running throughout the week-end preceding the invasion that a number of fast motor launches carrying supersonic buoys were engaged in laying them off the French shore. They were to guide our ships through the minefields with which the French coastal waters were thickly sown and past submerged wrecks and other obstacles. By that time the buoys as first used in the invasion of Sicily had been further developed at Chelmsford, particularly in the direction of absolute reliability, the sine qua non of an apparatus of this kind. Great pains had been taken therefore to make these buoys absolutely efficient. For example, the mechanism was so designed that a final test could be made before screwing the top down. No more than that could be done in the place of manufacture. But one more safeguard was possible, namely, a final test with the buoys submerged and in position. Therefore, when each buoy was laid at its working depth, a hydrostatic switch caused the transmitter to inform the laying vessel - a fast motor launch - that the buoy was well and truly “alive”. For the Invasion, the Mark IV buoy was used, and the meticulous care taken both in design and manufacture then gave a hundred per cent performance. All buoys laid functioned without failure throughout the great operation.

 

RADAR OR BUOY?

Now, it may appear curious that the Royal Navy, having the use of radar to guide its vessels in through the minefields off the French shore, elected for the Marconi supersonic buoy. Two considerations determined that choice, and are of interest. First, while radar offered complete efficiency, it did not provide the essential secrecy. For the enemy was able to receive the pulses, and thus be made aware of the Armada’s approach. The second reason was the circumstance that the Marconi Company’s supersonic buoy had already demonstrated its reliability, and thus offered a good alternative method free of the limitation attaching to radar for this particular purpose.

 

Some weeks after the invasion an Admiralty officer visited the Company's Works and was brought by its Chairman, Admiral Grant, into the workshops. There he told the people that the buoys: “Did every single thing expected of them”.