[modeleng] Re: scottish inventions

Kenny,
>Physicist, Sir Robert Watson-Watt, was the mind behind the radar network 
on 
the coast of England that detected incoming German aircraft in World War 
II. 
He had worked on the radio detection of thunderstorms (hazardous to 
aviators) during World War I. In 1935 he proposed a method for locating 
aircraft by a radio-pulse technique. The radar system was invaluable to 
the 
defense of Britain during the Battle of Britain in 1940. It operated day 
and 
night over a range of 40 miles, giving the Royal Air Force information 
about 
the height and bearing of German planes.<

That's what he gets credit for, not what he did. He was the Director of 
the Radio Research station at Slough (back in the days when industry was 
supported by the Department of Scientific and Industrial Research)when he 
was asked by the Tizard committee to calaculate if a wireless death ray 
was practicable. He got one of his men to do the calculations: the result 
was that it was impossible to generate sufficient power for a death ray, 
but that it should be possible to generate enough  to detect a reflection 
from aircraft. W-W reported this, and so it led to the famous trial with 
the Daventry transmitter of the BBC on 6Mc/s (as it was then) and a 
Heyford bomber. The measurement of distance by using a pulse technique was 
nothing new, having been used back in 1923 by Kennelly and Tuve for 
measuring the height of the ionosphere. His work on thunderstorm location 
was also hardly invnetive, as it used a Bellini-Tosi direction finding 
system (invented 1903) coupled to a CRT instead of a goniometer - and that 
was suggested before W-W used it. R.V.Jones is the not the only one, by 
the way, to have been pretty scathing about Watson-Watt and his ability to 
take credit for other people's work. There was also the occasion when W-W 
asked the Air Chief Marshall how he would like 500 superb airborne radar 
sets: the response was 'I'll settle for ten that work!'

The CH (Chain Home) was a pretty crude system in some ways: it relied on 
switching reflectors in and out of circuit to obtain the general 
direction, and manual goniometers to measure bearing and vertical angle. 
It possibly had a slight military advantage  in that it was a multistatic 
radar, with the receivers in different places to the transmitters, so 
possibly being more difficult to knock out. In many respects, the German 
Freya on 120Mc/s  was a better radar, although the lack of a DC restorer 
in the video circuits made it easy to jam. Where the British system was 
better was the integration of the radar into an air defence system, and 
W-W wasn't the architect of that, either.

Sorry, Kenny, but Watson-Watt wasn't anywhere near as good an inventor as 
he got the credit for.

Peter Chadwick
Swindon.
(Radio engineer by profession - if you hadn't guessed!)



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