Robert Watson-Watt, the Engineer Who Saved Great Britain

World War I was “the war that will end war,” according to the English author H. G. Wells: “This, the greatest of all wars, is not just another war—it is the last war!” His optimistic prophecy was just one more source of bitterness as Great Britain, not even two decades after signing the Treaty of Versailles, was preparing for another armed conflict with Germany.

Aviation was a minor factor in the outcome of the First World War. Aeronautical technology was developing rapidly, however, and by the mid-1930s, the British government recognized that Germany’s superior air force was a serious threat to national security. To promptly and effectively engage incoming enemy aircraft, British pilots needed two things: early warning and location data. The Chain Home radar system, made possible by the work of electrical engineer Robert Watson-Watt, provided both.

 

Robert Watson-Watt. Image courtesy of Historic UK

 

Lightning and Death Rays

Born in 1892, Robert Watson-Watt and his working-class parents must have had a relatively quiet life as Robert excelled at the local high school in a small town called Brechin, near the east coast of Scotland. The shadows of war were looming, though, by the time he received his B.Sc. in electrical engineering from the University of St. Andrews. The year was 1912, and after graduating, he continued to study “wireless telegraphy,” in other words, radio communication.

In 1915, the Great War was raging, and military aviation was in its infancy. Among the dangers to aircraft and pilots were thunderstorms; if you’ve seen photographs of planes in service toward the beginning of World War I, you can imagine what would happen if these wood-and-fabric flying machines were buffeted by high winds or struck by lightning. 

 

Planes like this were impressive feats of engineering for the time, but I wouldn’t want to fly one into a storm. Image courtesy of Wikimedia Commons

 

Robert Watson-Watt, at this time an employee of the British Meteorological Office, was applying his engineering expertise to the problem of helping pilots avoid dangerous storms. His system used an oscilloscope and a rotating antenna to detect the electrical disturbances caused by lightning strikes, and he recognized the potential for something far more significant: with the addition of a transmitter, a system like this could locate airplanes instead of storms.

Another step toward the first tactical radar system occurred when the British government asked Watson-Watt to investigate the possibility of an RF death ray. Rumors suggested that the Germans were developing an electromagnetic weapon that could disable enemy aircraft—it would have been intimidating indeed if land-based radio waves could detonate a plane’s munitions, destroy its electrical systems, or vaporize its pilot. Watson-Watt reported that such a weapon was not feasible, but he offered an alternative: an RF system that would detect enemy aircraft rather than neutralize them.

 

Chain Home and the Battle of Britain

Robert Watson-Watt wanted to be remembered as the man who invented radar. Without getting into the details of the controversy, I’ll say that “inventor of radar” is probably an overly generous title. However, Watson-Watt was the central figure in the development of the world’s first large-scale, successfully implemented radar system, and this seems like a sufficiently meritorious achievement—especially since without this system, Great Britain would probably have lost the Battle of Britain and, consequently, the entire war.

Various scientists, including Nikola Tesla and Guglielmo Marconi, had explored the possibility of radar in one form or another. Watson-Watt’s approach to radio-based, long-distance detection used relatively high-frequency (megahertz-range) pulsed transmissions in conjunction with operators who could translate received signals into actionable information. He demonstrated aircraft-tracking capability during a field test in 1935, and by 1938, three radar systems were fully functional. These three installations were the beginning of Chain Home, a network of radar stations that Watson-Watt devised as a means of protecting large sections of England’s southern and eastern coastline. By the end of the war, the network included 53 stations.

The pulsed transmissions produced by the Chain Home equipment allowed operators to determine distance by measuring the time delta between Tx and Rx signals. The configuration of the antenna installations provided multiple detection points for a single target, and with the help of trigonometry, operators could calculate the target’s range, bearing, and altitude.

 

The Chain Home radar units were not the sort of technology that we would nowadays consider “user-friendly.” Image courtesy of Wikimedia Commons

 

Though the Chain Home radar design seems fairly straightforward when you consider only the high-level functionality, we must not underestimate Watson-Watt’s engineering accomplishments. These systems were extraordinarily complex, given the technical limitations of the time, and they were marvelously effective. Chain Home consistently gave British pilots an additional twenty minutes to intercept approaching German aircraft; according to historian John Waller, it is “almost certain” that without Chain Home, the Royal Air Force would have lost the Battle of Britain.

 

Engineer, War Hero, Knight

I usually don’t think of electrical engineering as a career that puts you on the path to knighthood, but Sir Robert Watson-Watt—knighted by King George VI in 1942—was an exception. An accolade of this nature seems to me a fitting recompense for his tremendous contribution to the war effort. 

After World War II, Watson-Watt worked as an independent consultant in North America, eventually returning to the U.K. and living there until his death in 1973. In 2014, Watson-Watt’s hometown unveiled a statue of their heroic engineer. It depicts him holding a radar tower in one hand and an RAF Spitfire in the other, reminding us of the numerous British pilots—and civilians—he helped to save.

 

Memorial honoring Watson-Watt in Angus, Scotland. Image (modified) courtesy of Kevan Dickin [CC BY-SA 4.0]