Robert Watson-Watt

Britannica Concise Encyclopedia: Sir Robert Alexander Watson-Watt

(born April 13, 1892, Brechin, Scot. — died Dec. 5, 1973, Inverness) Scottish physicist. He began as a meteorologist working on devices for locating thunderstorms. As head of the radio department of Britain's National Physical Laboratory (1935), he worked on aircraft radio location and could locate planes at a distance of about 80 mi (110 km) by beaming radio waves at them, receiving reflections of the waves, and calculating distance by elapsed time. This led to the design of the world's first practical radar system, a vital element in the defense of Britain against German air raids during World War II. His other contributions include a cathode-ray direction finder used to study atmospheric phenomena, research in electromagnetic radiation, and inventions used for flight safety.

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Scientist: Sir Robert Alexander Watson-Watt

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British physicist (1892–1973)

Watson-Watt was born Robert Watt at Brechin in Scotland. The Watson part of his name came from his mother's family and the hybrid Watson-Watt was adopted in 1942 on receipt of his knighthood. He was the son of a carpenter and was educated at the University of St. Andrews. After graduating in 1912 he immediately joined the faculty but found his academic career disrupted by World War I. He spent much of the war working as a meteorologist at the Royal Aircraft Establishment, Farnborough, attempting to locate thunderstorms with radio waves.

He remained in the scientific civil service after the war and in 1921 was appointed superintendent of the Radio Research Station at Slough. In 1935 he was asked by the Air Ministry if a ‘death ray’ could be built – one capable of eliminating an approaching enemy pilot. Watson-Watt asked a colleague to calculate how much energy would be needed to raise a gallon of water from 98°F to 105°F at a distance of a mile, i.e., a significant rise in body temperature. He advised the Ministry that the energy needed outstripped the available technology.

Watson-Watt also pointed out that Post Office engineers had noted interference in radio reception as aircraft flew close to their receivers. Interference of this kind, he suggested, could perhaps be used to detect the approach of enemy aircraft. In 1935 he submitted an important paper, The Detection of Aircraft by Radio Methods, to Tizard at the Ministry. Watson-Watt was normally a man, it was said, who could never say in one word what could be said in a thousand. This time, however, the report was terse and to the point. Tizard asked for a demonstration. In February 1935 the BBC short-wave transmitter at Daventry was successfully used to identify the approach of a Heyford bomber eight miles away.

Tizard moved quickly. Watson-Watt was invited to set up a research station at Bawdsley in Suffolk to develop radio detection and ranging; the acronym ‘radar’ was first recorded in use in the New York Times in 1941.

The principles behind radar are relatively simple. Radio waves are reflected strongly off large objects such as airplanes. The difficulty was that very little, something of the order of 10^–12, of the transmitted signal would be picked up by the receiving antennae. Both high transmitting power and high amplification would therefore be needed. Watson-Watt assembled a talented team at Bawdsley and by the outbreak of World War II an operational chain of eight stations, known as ‘Chain Home’, defended Britain's eastern and southern coasts. They operated in the high-frequency bands and required very visible 360-foot-high transmitters and 240-foot-high receivers.

Watson-Watt left Bawdsley in 1938 for the Air Ministry and the post of director of communication development. His main task was to make radar workable, to ensure that it was acceptable to the RAF and that they could actually operate the new equipment. He also had to arrange for the manufacture of the relevant transmitters, receivers, and electron tubes.

He finally left the civil service in 1945 to set up as a consultant. He was also invited to give evidence before the Royal Commission on Inventors on behalf of his colleagues and himself. After speaking for six days Watson-Watt was awarded £52,000 for his work on radar.

Biography: Sir Robert Alexander Watson-Watt

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Sir Robert Alexander Watson-Watt (1892-1973) was a British scientific civil servant who pioneered the development of radar.

Robert Watson-Watt, the youngest son of a carpenter, was born on April 18, 1892, at Brechin, Angus, Scotland. He studied electrical engineering and physics at University College, Dundee, and became assistant to the professor of natural philosophy there in 1912. In 1915 he was assigned to the Meteorological Office to assist in the location of thunderstorms by their radio emissions for the information of aviators. This led to fundamental research into atmospherics (the transient radio emissions from lightning discharges) at the Radio Research Station, Slough, England, under the aegis of government departments. By the 1930s much had been achieved there through inter alia, the development of the cathode-ray oscillograph and aerial systems. Atmospherics were located by direction finding at two or more receivers and associated with the movements of cold-air fronts.

In 1935 Watson-Watt was asked to consider the possibility of radio destruction of aircraft (the "death ray"), but with A. F. Wilkins he soon confirmed its impracticability. However, further calculations indicated the possibility of radio detection, and in February 1935 Watson-Watt's memorandum on the "location of aircraft by radio methods" was taken up by the Tizzard Committee for the scientific survey of air defense. Watson-Watt showed that a metal aircraft approximated to a linear oscillator and indicated that the secondary radiation induced when aircraft were illuminated from the ground with 50-meter radiation could be detected at ranges of tens of miles. He proposed transmitting short pulses both to increase peak output and to use the time delay in the return of the echo from the aircraft to determine range. Cross bearings from other stations could fix positions. Pulse techniques had been developed for echo-sounding the generally reflective ionosphere, but extensive refinement was required for its application to the detection of small targets. At an establishment on the North Sea coast Watson-Watt, with Wilkins, L. H. Bainbridge-Bell and E. G. Bowen, brought the system to reality and added direction finding from crossed horizontal halfwave aerials. By 1936 a home defense chain of radar stations had been approved; largely completed by 1938, it played a vital role in the Battle of Britain.

The development of radar was very much a team effort with Watson-Watt as captain. Throughout the war he was increasingly concerned in coordinating the expanding effort in the radar field. He visited the United States in 1941-1942 as an adviser. In 1946 he left government service to practice as a consultant. He was elected a fellow of the Royal Society in 1941 and was knighted in 1942.

Watson-Watt claimed the invention of radar, but, as with other classic science-based inventions, it evolved. There were precursors and simultaneity of discovery in several countries. Suffice it to say that no other saw the possibilities so clearly, and no government took up the implications more quickly. Perhaps more than any other in the history of invention, Watson-Watt was the right man in the right place at the right time.

For his work, Watson-Watt received the United States Medal for Merit in 1946. He lived in Tuxedo, New York, and briefly in Canada. But he died December 5, 1973, in his homeland of Scotland after a long illness.

Robert Alexander Watson-Watt

Born	13 April 1892 Brechin, Angus, Scotland, UK
Died	5 December 1973 (aged 81) Inverness, Scotland, UK
Known for	radar

Early years

Born in Brechin, Angus, Scotland, he was a descendant of James Watt, the famous engineer and inventor of the practical steam engine. After attending Brechin High School ^[1], he was accepted to University College, Dundee (which was then part of the University of St Andrews but became the University of Dundee in 1967). He graduated with a BSc in engineering in 1912, and was offered an assistantship by Professor William Peddie. It was Peddie who encouraged him to study radio, or "wireless telegraphy" as it was then known.

Early experiments

In 1915 Watson-Watt wanted a job with the War Office, but nothing obvious was available in communications. Instead he joined the Meteorological Office, who were interested in his ideas on the use of radio for the detection of thunderstorms. Lightning gives off a radio signal as it ionizes the air, and he planned on detecting this signal in order to warn pilots of approaching thunderstorms.^{[citation needed]}

His early experiments were successful in detecting the signal, and he quickly proved to be able to do so at long ranges. Two problems remained however. The first was locating the signal, and thus the direction to the storm. This was solved with the use of a directional antenna, which could be manually turned to maximize (or minimize) the signal, thus "pointing" to the storm. Once this was solved the equally difficult problem of actually seeing the fleeting signal became obvious, which he solved with the use of a cathode-ray oscilloscope with a long-lasting phosphor.^{[citation needed]} Such a system represented a significant part of a complete radar system, and was in use as early as 1923. It would, however, need the addition of a pulsed transmitter and a method of measuring the time delay of the received radio echos, and that would in time come from work on ionosondes.

At first he worked at the Wireless Station of Air Ministry Meteorological Office in Aldershot, England. In 1924 when the War Department gave notice that they wished to re-occupy their Aldershot site, he moved to Ditton Park near Slough (Berkshire). The National Physical Laboratory (NPL) already had a research station there. In 1927 they were amalgamated as the Radio Research Station, with Watson-Watt in charge. After a further re-organisation in 1933, Watson-Watt became Superintendent of the Radio Department of NPL in Teddington.

RADAR

The air defence problem

In 1933 the Air Ministry had recently set up a committee to advance the state of the art of air defence in the UK. In World War I the Germans had used Zeppelins as long-range bombers over London and other cities and defences had struggled to counter the threat. Since that time aircraft capabilities had improved considerably, and existing weapons were unlikely to have any effect on a raid.

The prospect of aerial bombardment of civilian areas was causing the government anxiety with modern heavy bombers able to approach from altitudes that anti-aircraft guns were unable to reach.^[2] With the enemy airfields only 20 minutes away, the bombers would have dropped their bombs and be returning to base before the intercepting fighters could get to altitude. The only solution would be to have standing patrols of fighters in the air at all times, but with the limited cruising time of a fighter this would require a gigantic standing force. A plausible solution was urgently needed.

Nazi Germany claimed to have a "death-ray" which used radio waves, that was capable of destroying towns, cities and people. The committee's chair, H.E. Wimperis, visited Watson-Watt at Teddington in 1934, ask about possibly building their version of a death-ray, specifically to be used against aircraft. Watson-Watt quickly returned a calculation carried out by his assistant, Arnold Wilkins, showing that the device was impossible to construct, and fears of a Nazi version soon vanished. However he also mentioned in the same report "Meanwhile attention is being turned to the still difficult, but less unpromising, problem of radio detection and numerical considerations on the method of detection by reflected radio waves will be submitted when required."^[3]

Aircraft detection and location

Wilkin's sketch of the Daventry Experiment

Memorial at the site of the first successful RADAR experiments. 52°11′46″N 1°03′00″W / 52.195982°N 1.050121°W

Closeup of memorial plaque

On 12 February 1935, Watson-Watt sent a memo of the proposed system to the Air Ministry, entitled Detection and location of aircraft by radio methods. Although not as exciting as a death-ray, the concept clearly had potential and Watson-Watt was promptly asked for a demonstration by the committee, chaired by Sir Henry Tizard.^[4] This was ready by 26 February and consisted of two receiving antennas located about ten km away from one of the BBC's shortwave broadcast stations at Daventry. The two antennas were phased such that signals travelling directly from the station cancelled themselves out, but signals arriving from other angles were admitted, thereby deflecting the trace on a CRT indicator (passive radar).^[5] Such was the secrecy of this test that only three people witnessed it: Watson-Watt, his assistant Arnold Wilkins, and a single member of the committee, A.P. Rowe. The demonstration was a success; on several occasions a clear signal was seen from a Handley Page Heyford bomber being flown around the site. Most importantly, the prime minister, Stanley Baldwin, was kept quietly informed of radar's progress.

Only two weeks later Wilkins left the Radio Research Station with a small party, including Edward George Bowen, to start further research at Orford Ness. On 2 April 1935, Watson-Watt was granted a patent for radar. By June they were detecting aircraft at 27 km, which was enough for scientists and engineers to stop all work on competing sound-based detection systems. By the end of the year the range was up to 100 km, at which point plans were made in December to set up five stations covering the approaches to London.

One of these stations was to be located on the coast near Orford Ness, and Bawdsey Manor Research Station was set up there to become the main centre for all radar research. A policy of no wastage using existing available components given the limited time they had, opposed to longer amount of time needed to create new components, along with a relaxed and informal atmosphere enabled Watson-Watt and his team the innovation to create prototype radars. So long prototype radars were in workable condition they were put into production.^[3] They soon conducted "full scale" tests of a fixed radar radio tower system would soon be known as Chain Home, an early detection system that attempted to detect an incoming bomber by radar.^[3]^[6] The tests were a complete failure, with the fighter only seeing the bomber after it had passed its target. The problem was not the radar, but the flow of information from trackers from the Observer Corps to the fighters, which took many steps and was very slow. With Henry Tizard, Patrick Blackett, Hugh Dowding immediately set to work on this problem constructing a 'command and control air defence reporting system' with several layers of reporting that were eventually sent to a single large room for mapping. Observers watching the maps would then tell the fighter groups what to do via direct communications.^[3]

By 1937 the first three stations were ready, and the associated system was put to the test. The results were encouraging and successful, an immediate order by the government to commission an additional 17 stations was given, forming the resultant a chain of fixed radar towers along the east and south coast of England.^[3]^[6] By the start of World War II 19 were ready to play a key part in the Battle of Britain, and by the end of the war over 50 had been built. The Germans were aware of the construction of Chain Home but were not sure of their purpose. They tested their theories with a flight of LZ 130, the Graf Zeppelin II, but concluded the stations were a new long-range naval communications system.

As early as 1936 it was realized that the Luftwaffe would turn to night bombing if the day campaign did not go well, and Watson-Watt had put another of the staff from the Radio Research Station, Edward Bowen, in charge of developing a radar that could be carried by a fighter. Night time visual detection of a bomber was good to about 300 m, and the existing CH systems simply didn't have the accuracy needed to get the fighters that close. Bowen decided that an airborne radar should not exceed 90 kg (200 lb in weight, 8 ft³ (230 L) in volume, and require no more than 500 watts of power. To reduce the drag of the antennas the operating wavelength could not be much greater than one m, difficult for the day's electronics. "AI" - Airborne Interception, was perfected by 1940, and were instrumental in eventually ending the Blitz of 1941. Bowen also fitted airborne radar to maritime patrol aircraft (known in this application as "ASV" - Air to Surface Vessel) and this eventually reduced the threat from submarines.^{[citation needed]}

Contribution to World war II

In his English History 1914-1945, historian A. J. P. Taylor paid the highest of praise to Watson-Watt, Sir Henry Tizard and their associates who developed and put in place radar, crediting them with being fundamental to victory in World war II.

Sir Robert Alexander Watson-Watt, ca. 1944

In July 1938 Watson-Watt left Bawdsey Manor and took up the post of Director of Communications Development (DCD-RAE). In 1939 Sir George Lee took over the job of DCD, and Watson-Watt became Scientific Advisor on Telecommunications (SAT) to the Air Ministry, travelling to the USA in 1941 in order to advise them on the severe inadequacies of their air defense efforts illustrated by the Pearl Harbor attack. His contributions to the war effort were so overwhelming that he was knighted in 1942.

Later years

Ten years after his knighthood, Watson-Watt was awarded £50,000 by the British government for his contributions in the development of radar. He established a practice as a consulting engineer. In the 1950s moved to Canada. Later he lived in the USA, where he published Three Steps to Victory in 1958.^{[citation needed]} Around 1958 he appeared as a mystery challenger on the American television program To Tell The Truth.

On one occasion, late in life, Watson-Watt reportedly was pulled over in Canada for speeding by a radar-gun toting policeman. His remark was, "Had I known what you were going to do with it I would never have invented it!"^{[citation needed]} He wrote an ironic poem ("Rough Justice") afterwards:

"Pity Sir Robert Watson-Watt,/

strange target of this radar plot/

And thus, with others I can mention,/

the victim of his own invention./

His magical all-seeing eye/

enabled cloud-bound planes to fly/

but now by some ironic twist/

it spots the speeding motorist/

and bites, no doubt with legal wit,/

the hand that once created it."^[7]

Marriages

Watt was married^[8] on 20 July 1916 in Hammersmith, London to Margaret Robertson, the daughter of a draughtsman; they later divorced and he re-married[1] in 1952 in Canada.

He returned to Scotland in the 1960s. In 1966, at the age of 72, he proposed to Dame Katherine Trefusis-Forbes, who was 67 years old at the time and had also played a significant role in the Battle of Britain as the founding Air Commander of the Womens Auxiliary Air Force, which supplied the radar-room operatives.

They lived together in London in the winter, and at "The Observatory" – Trefusis-Forbes' summer home in Pitlochry, Perthshire, during the warmer months. They remained together until her death in 1971. Watson-Watt died in 1973, aged 81, in Inverness. Both are buried in the church yard at Pitlochry.

References

^ "Sir Robert Watson-Watt". Dick Barrett. http://www.radarpages.co.uk/people/watson-watt/watson-watt.htm. Retrieved 2008-02-26.
^ Evans, R.J. (18 September 2008). "Hitler and the origins of the war, 1919-1939". Lecture transcript. Gresham College. http://www.gresham.ac.uk/event.asp?PageId=108&EventId=775. Retrieved 16 August 2009.
^ ^a ^b ^c ^d ^e Corrigan, R. (24-25 September 2008) (pdf). Airborne minefields and Fighter Command's information system. Andrés Guadamuz/The University of Edinburgh, School of Law. http://www.law.ed.ac.uk/ahrc/gikii/docs3/corrigan.pdf. Retrieved 16 August 2009.
^ "Robert Watson-Watt". The Radar Pages. http://www.radarpages.co.uk/people/watson-watt/watson-watt.htm. Retrieved 2007-12-14.
^ "Passive Covert Radar - Watson-Watt's Daventry Experiment Revisited". IET. http://tv.theiet.org/technology/communications/219.cfm. Retrieved 2008-12-13.
^ ^a ^b "Tribute plan for radar inventor". BBC. 1 November 2006. http://news.bbc.co.uk/2/hi/uk_news/scotland/tayside_and_central/6104186.stm. Retrieved 16 August 2009.
^ "Rough Justice" (poem)
^ Entry number 115 in the marriage register of St Saviour's church, Hammersmith.

External links

Deflating British Radar Myths of World War II A comparison of contemporary British and German radar inventions and their use
Radar Development In England
Sir Robert Alexander Watson-Watt's biography

Sources

v • d • e Aerial defence of the United Kingdom during the Second World War
Overview documents
Royal Air Force \| Royal Canadian Air Force \| Strategic bombing \| Night fighter
Prominent people
Hugh Dowding \| Charles Portal \| Cyril Newall \| Trafford Leigh-Mallory \| Keith Park \| R V Jones \| Sholto Douglas \| Robert Watson-Watt
Organisation and units
No. 10 Group RAF \| No. 11 Group RAF \| No. 12 Group RAF \| No. 13 Group RAF Anti-Aircraft Command \| RAF Balloon Command \| RAF Coastal Command \| RAF Fighter Command \| RAF Bomber Command Battle of Britain Airfields \| Eagle Squadrons \| Royal Observer Corps \| Women's Auxiliary Air Force
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Battle of Britain \| The Blitz \| Baedeker raids \| Operation Crossbow
Aircraft, technology and tactics
Beaufighter \| Defiant \| Hurricane \| Meteor \| Mosquito \| Spitfire \| Tempest \| Typhoon
Barrage balloon \| Battle of the Beams \| Big Wing \| Chain Home \| Radar \| German V weapons
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