Usage of radars at Russian front

[Glider]

Thanks to one and all. A week ago I knew next to nothing about this topic, now I feel pretty well clued up.

 

[Alamotex]

Hello
British and Commonwealth ground radar delivers to SU from Finnish soures

Up to 31 March 44 302 GL Mk IIs, 15 British made and 29 Canada made GL Mk IIIs

On SU radar set production, see Soviet Development of Radar to 1945 - OnAirpower.org

Juha

I am very interested to know how many Canadian GL III(c) gunlaying radars were shipped to Russia in WW II. Unclear whether the 29 quoted above includes all Lend Lease shipments that were unloaded for deployment and excludes those that went down with ships in the Murmansk convoys ? It has been assumed that the GL III(c) located at the RCA museum in Shilo,Manitoba, Canada is the only one known to exist with some of the original electronics still in place. Anyone, know of any examples that are in museums or in private collections ?

 

[Siegfried]

Radar - The Soviet Union WWII Part II
All sorts of historical detail on this site.

The Luftwaffe had mobile Freya early warning radar sets in Russia during June 1941. It appears the Soviets had a fixed radar set operating at Leningrad. Like almost everything else, production of Soviet radar sets was badly disrupted during 1941 and 1942 when the Heer over ran the western Soviet Union. Hence the importance of Lend-Lease supplied radar equipment.

Louis Browns "A Radar History of WW2: technical and military imperatives" covers the Soviet Radar Programm.

Basically the history of Soviet radar development is characterised by
1 Large numbers of Technicians/Scientists and Engineers ending up in Gulags.
2 In fighting between Soviet Bueros: If a project didn't belong to a buero it was hated.

The Russians in fact invented the cavity magnetron, the Germans (who knew of it anyway) refered to it as a British copy of a Russian patent. However their RUS 1 radar was nearly useless while the RUS 2 required the two antenas to be 1km apart, with the yagi's pointing direction being synchronised by a cable. This is an indication of how poor Soviet high frequency work had degenerated from their early magnetron work as they could not even master placing the antena close together let alone sharing a Transmit Receive antena with radars using 4m wavelenths.

Basically the Soviets relied in British radars or copies thereoff.

The Germans were years ahead, only falling behined the Western Allies due to their abandonment of microwave work, which was begining to show good results. The Germans had accurate tracking radars of good resolution not matched till the SCR-584

 

[parsifal]

The Russians in fact invented the cavity magnetron, the Germans (who knew of it anyway) refered to it as a British copy of a Russian patent.

if you are referring to the magnetron developed in the 1920s, this was purely a research project, undertaken by a number of universities more or less simultaneoulsy. The research failed to solve fundamental transmission problems and the research faltered

By 1937 Randall was recognized as the leading British worker in his field, and was awarded a Royal Society fellowship to the University of Birmingham, where he worked on the electron trap theory of phosphorescence in Professor Marcus Oliphant's physics faculty When the war began in 1939 Randall transferred to the large group working on centimeter radar. At the time limited transmitter output was the greatest single obstacle in the development of this type of radar.

Simple two-pole magnetrons had been developed in the 1920s (almost simulataneously by separate researchers) but gave relatively low power outputs. A more powerful multi-cavity resonant magnetron had been developed in 1935 by Hans Erich Hollmann in Berlin, however this set was still of relatively low power and not a usable design. By 1940 Randall and Dr Harry Boot produced a working prototype similar to Hollman's cavity magnetron, but added liquid cooling and a stronger cavity. However Randall and Boot soon managed to increase its power output 100-fold compared to Hollmanns research, moreover Hollmann prototype would never have been able to reach the same powe outputs as the British prototype, without thye liquid cooling and the stronger cavity device. As Prof. W. E.Burcham recollects:

"John Randall and Harry Boot, two young physicists were assigned to the task in 1939. Within two months (21 February 1940) they had produced a new kind of magnetron, one with eight concentric cavities… Randall got the inspirational idea of using eight cavities when he researched the design of the original Hertz oscillator which was an open single ring. Randall saw that this structure could be extrapolated into a cylinder and then into eight resonating chambers".

So, like all things, there was a certain amount of ground research undertaken by a number of differing nationalities. Theoretical research tends to do that. Thats a long way from developing an operational workable design, which is an exclusively british achievement undertaken in wartime conditions, in which wartime restrictions and legislation prevented the sharing of such research. Germany and Russia lagged so far behind, that for practical purposes they never produced a working design of the apparatus. suggesting it was not worth the effort is also very much into revisionist history. The Nachtjager crews were flying at a considerable disadvantage viz a viz British NF crews because of the limitations of their airborne radars. they did eventually get around to producing centimetric radars, by which time it was far too late.

The Russians never came close to developing a cavity magneron. They copied British technology post war, the same as they did with British jet technologies, when they reverse engineered the nene.

 

[Siegfried]

if you are referring to the magnetron developed in the 1920s, this was purely a research project, undertaken by a number of universities more or less simultaneoulsy. The research failed to solve fundamental transmission problems and the research faltered

By 1937 he was recognized as the leading British worker in his field, and was awarded a Royal Society fellowship to the University of Birmingham, where he worked on the electron trap theory of phosphorescence in Professor Marcus Oliphant's physics faculty.[citation needed] When the war began in 1939 Randall transferred to the large group working on centimeter radar. At the time limited transmitter output was the greatest single obstacle in the development of this type of radar.

.

Let me state most emphatically: Randall and Boot of Britain did not develop or invent the high power multicavity magnetron. Both the Russians and Japanese did that first.

I am not refering to the split anode magentron.

Yoji Ito developed a water cooled magnetron 1 whole year before Randall and Boot. His water cooled magnetrons enterered service as the type 22 radar (see the radar section on ww2 aircraft net) they were in use only about 6 months after Britain. Sheiguero Nakajima, his brother, has left a few memoirs (eg IEEE oral history) about. The japanese navy failed to take full advantage of the gold it had.


Alekseev and Mailarov invented the Multicabity magnetron in the Soviet Union in 1937. When the Germans recovered a H2S magnetron they attributed it to the russian patent.
The Russians were well on the way to pulse radar in 1933, possibly even magnetron radar, before purges runined thier chances.

See Browns "Radar History, technical and military imperatives" you can get on Kindle (you can down load kindle software for you PC don't need a Kindle)

German radar was excellent. They had the first effective gunlaying AAA radar (Wurzburg) and unlike the British deployed a track locking radar (FuSE 64 Mannheim).

Seetakt DID have blind fire capabillity, from about 41 onwards.

The German microwave program targeted 5cm using magnetrons (they could produce about 4kW power, but it was tunable) and 27cm using a new type of triode (good for about 25kW and latter 100kW) though the triode LD7 could also produce about 15kW pulses at 9cm. By the end of 1942 they simply ran out of resouces and put their money into conventional radars or sending their technicians into the militar. The Germans also had a 18cm 12kW magnetron in 1940 (multicabivity). See Doering "A history of microwave tube development in Germany" though if General Martini's request had of been granted research down to 1.5cm would have continued (Martini organised the channel Dash jamming)

The Germans used coherant radars with grid modulation where the pulse is coherant with a contrinous reference in the transmitter so that the range information came not only from the time of the start of the pulse but its phase as well. The British type 284 radar and all microwave radars used anode modulation where the pulse is generated by dumping a charge into the triode in a similar fashion to a spark plugs. A short high power pulse is required whereas the weaker German tubes could compensate via a longer pulse thereby getting range and resolution out of phase.

German radar such as SN-2 performed much better than microwave radars and could far quickly find targets. Their disadvantage in range close to the ground was not often important: they were after bombers. The weakness in jam resistance only showed up latter. In fact German night fighter crews were aksing for radars with wider acquistion angles and SN-2 was one solution) (which also bypassed jamming)

Had the Germans have continued with their microwave program they certainly would have succeded. They had a 18cm set called "Eisbaer" running in 1942. (Telefunken) they just couldn't see the point.

The archoles heal of longer wavelength radars was their wide beams vulnerabillity to jamming and their lack of resolution unless with large antena.


Its worht listening to Bernard Lovell (H2S designer) on the German discovery of the Magnetron
http://www.webofstories.com/play/17816?o=MS
http://www.webofstories.com/play/17814?o=R

 

[parsifal]

Its more complicated than that. Certainly I make no claim that Randall and Boot "invented" the Cavity Magnetron. US sources claim that GE were the first to do that, in 1921, but the generally accepted version is that the pioneer work was done by a German, Hollmann I think.

Neither the Russian or the Japanese versions of the magnetron were at all efficient or workable. Which kinda explains a lot in itself since nothing came from either strands of research. The German failure is harder to explain. They were on the right track, and were years ahead of anybody, but then just let the whole thing fall away. Whilst the germans did go on to produce decent radars, and at the end superior radars, for the most part their operational types that were fielded were a generation behind those of the allies. This is difficult to understand why,. German research and prototype development was cutting edge and in many respects ahead of the allies.

Arthur E Bauer a noted authority in this field makes the following observations:

"I have come to the, maybe harsh, conclusion that the subject of the recent CAVMAG2010 Conference should not have been on: 70 Years of Cavity Magnetron, though, more relevantly on "70 Years of Oxide Cathode in Cavity Magnetron". As it was the application of oxide cathodes that allowed high output power, without an oxide cathode they never would have obtained it. It was Gutton who brought this knowledge to Megaw and others. And, it was Megaw who finally transformed the rudimentary Birmingham device into a versatile, call it decisive, device. The claim that Randall and Boot have invented the cavity resonator magnetron must be regarded being simply nonsense! This technique was, as we have seen, known before the war. Maybe not always focussing on high output power, though it existed! It was the combination of oxide cathode in conjunction with cavity resonators that made the break-through which allowed highly effective cm radars. Certainly a war winning device!

To be honest - one very significant point of the Randall and Boot group was that they introduced the only appropriate way of picking up the generated EM force by means of an inductive loop placed inside the output cavity. The Lorenz cavity magnetron as well as the Japanese cavity power magnetron of the 1930s were only having electrical pickup stubs. Which is very ineffective in an inductive environment"

Therein lies the significance of the randall and Boot contribution. It was significant, to the point of being decisive, but not because they "invented" anything, rather they "developed" existing technologies into highly useful machines for war. All of the others failed to do that or, did it, but too late and too fitfully to make any difference

 

[alejandro_]

You can find quite a bit of documentation here, but it's in Spanish:

http://www.rkka.es/PVO/index_PVO.htm

 

[Siegfried]

Its more complicated than that. Certainly I make no claim that Randall and Boot "invented" the Cavity Magnetron. US sources claim that GE were the first to do that, in 1921, but the generally accepted version is that the pioneer work was done by a German, Hollmann I think.

Neither the Russian or the Japanese versions of the magnetron were at all efficient or workable. Which kinda explains a lot in itself since nothing came from either strands of research. The German failure is harder to explain. They were on the right track, and were years ahead of anybody, but then just let the whole thing fall away. Whilst the germans did go on to produce decent radars, and at the end superior radars, for the most part their operational types that were fielded were a generation behind those of the allies. This is difficult to understand why,. German research and prototype development was cutting edge and in many respects ahead of the allies.

Arthur E Bauer a noted authority in this field makes the following observations:

"I have come to the, maybe harsh, conclusion that the subject of the recent CAVMAG2010 Conference should not have been on: 70 Years of Cavity Magnetron, though, more relevantly on "70 Years of Oxide Cathode in Cavity Magnetron". As it was the application of oxide cathodes that allowed high output power, without an oxide cathode they never would have obtained it. It was Gutton who brought this knowledge to Megaw and others. And, it was Megaw who finally transformed the rudimentary Birmingham device into a versatile, call it decisive, device. The claim that Randall and Boot have invented the cavity resonator magnetron must be regarded being simply nonsense! This technique was, as we have seen, known before the war. Maybe not always focussing on high output power, though it existed! It was the combination of oxide cathode in conjunction with cavity resonators that made the break-through which allowed highly effective cm radars. Certainly a war winning device!

To be honest - one very significant point of the Randall and Boot group was that they introduced the only appropriate way of picking up the generated EM force by means of an inductive loop placed inside the output cavity. The Lorenz cavity magnetron as well as the Japanese cavity power magnetron of the 1930s were only having electrical pickup stubs. Which is very ineffective in an inductive environment"

Therein lies the significance of the randall and Boot contribution. It was significant, to the point of being decisive, but not because they "invented" anything, rather they "developed" existing technologies into highly useful machines for war. All of the others failed to do that or, did it, but too late and too fitfully to make any difference

I have to argue that there is still some mythology in this.

The Germans were quite aware of the use of thoriated cathodes to increase emissivity and made good use of them from early on eg in the RD12 tubes of the Hohetenweil radar. I regard it as somewhat of a feel good story to make the French feel good about having made some minor contribution. Whatever the pickoffs were in the Japanese magnetron (eg the M320) it produced sufficient power to power a 35km range surface search radar, the relatively low power level of the Japanese magnetrons was related to the fact that they were fabricated of sheet metal in glass tubes rather than made of solid machined metal thiugh they were still water cooled. The Japanese did have such magnetrons but in breath taking short sightedness avoided their use due to materials costs.

The Germans had great sucess producing radars in the 50cm to 80cm band at at time other nations were generally well behined. These radars worked quite well.

Magnetrons also have limitations, they are diodes with two terminals: you run power into them either contioniously or via a spark style discharge and they produced an oscilations.

Triodes can be controlled via a 3rd terminal called a grid so not only can they be switch on and off, they can be used to amplify, switch and to produce a pulse whose frequency and phase were related to a stable local oscilator in the transmiter. This allowed Wurzburg to incorporate the "Wurzlaus" pulse doppler circuit to resolve windows and for Seetakt to achieve excellent range resolution.

The new generation of 'disc triodes' overcame the limitations of vacuum tubes as follows
1 Grid spacings of a few thousandth of an inch to overcome the electron transit time issue
2 Special coatings to overcome secondary emission (where an electrod is indirectly heated)
3 Building the whole tube around coaxial technology (hence the disc seal ceramic technology)

This was the German program: it was about ready to produce a new generation of 25cm radars in 1942 when it was put on the back burner, all except a gun laying radar called "Euklid" FuMO 231 for the German navy which needed the smaller dish. Euklid worked well at 27cm, much time was wasted testing it with the 9cm H2S magnetron, which worked worse then the controllable disk triode. However after testing with 3cm magentrons Euklid worked better than the 27cm version.

So the Germans decided to follow a different path. For microwaves they went for tunable 5cm magnetrons, this was rather ambitious and slowed things down. Tunabillity came out of the fear of jamming ( policy after the bruneval raid)

Also Friedrich Kunhold, head of the Signals Branch of the German Navy, a physicist, who wanted to apply his sonar techniques using micowaves as early as 1931 and thereby hired Tonographie (latter GEMA) to realise his ideas. He did not get on the with Wilhelm Runge of Telefunken due to Runges mocking of his radar ideas despite Runge latter designing Wurzburg. The German navy kept GEMA to themselves as much as possible. Also despite having split anode magentron radars in 1934/5 it was found conventional tubes worked as welll

The Germans did have killowatt power multicavity magnetrons in 1940, they refered to them as 'rad magentron' or wheel magnetron. Typically 8 segments they lacked the optimal shape of the Boot magnetrons but still produced good power levels (18kW at 21cm)

There were also other issues, they had not great need of surface search radar, Seetakt and Hohtenweil (PPI) worked well. There was not belief that micwave radar was needed for airborn interception (9cm came out of the belief that a 75cm dish that could fit into a beaufighter would need a 15 degree beqm width) and so they did not stumble upon it other advantages in ground mapping and surface search.

The 27cm technology would have been competitive with allied 9cm technology (due to other advantages) and in fact these triodes could generate down to 5cm or less.

 

[renegate326]

Its more complicated than that. Certainly I make no claim that Randall and Boot "invented" the Cavity Magnetron. US sources claim that GE were the first to do that, in 1921, but the generally accepted version is that the pioneer work was done by a German, Hollmann I think.

It was done by the Germans,1935 Hans Erich Hollmann filed in Germany on November 27, 1935, a patent on the multi-cavity magnetron. US Patent 2,123,728 was granted on July 12, 1938, well ahead of John Randall's and Henry Boot's work in February 1940.Randal and Boot didn't invent anything. The invention of the Magnetron as an efficient transmitting tube by the US-american physicist Albert Wallace Hull in 1921.. Clearly radar was not invented in Britain !

 

[Wurger]

So the Wikipedia can lie... Cavity magnetron - Wikipedia, the free encyclopedia

"The cavity magnetron is a high-powered vacuum tube that generates microwaves using the interaction of a stream of electrons with a magnetic field. The first form of magnetron tube, the split-anode magnetron, was invented by Albert Hull in 1920, but it wasn't capable of high frequencies and was little used. The modern 'resonant' cavity magnetron tube was invented by John Randall and Harry Boot in 1940 at the University of Birmingham, England.[1] The high power of pulses from the cavity magnetron made centimeter-band radar practical, with shorter wavelength radars allowing detection of smaller objects. The compact cavity magnetron tube drastically reduced the size of radar sets[2] so that they could be installed in anti-submarine aircraft[3] and escort ships.[2]"

The Albert Wallace Hull's magentron wasn't the same that the one invented by John Randall and Harry Boot in 1940.

 

[parsifal]

Yes, its one thing to possess the research of sorts, and another to make it workable. Randall and boots were important in the development of the te4chnology because they took a theoretical concept and made it work, especially at high frequencies.

it probably a fair statement that the British did not invent radar, or the cavity magnetron. But it is a fair summation of the British effect. The British took existing strands of research, even patented idea, and then adpate or developed them into very efficient radars, that gave them a critical lead at a critical time

 

[renegate326]

Yes, its one thing to possess the research of sorts, and another to make it workable. Randall and boots were important in the development of the te4chnology because they took a theoretical concept and made it work, especially at high frequencies.

it probably a fair statement that the British did not invent radar, or the cavity magnetron. But it is a fair summation of the British effect. The British took existing strands of research, even patented idea, and then adpate or developed them into very efficient radars, that gave them a critical lead at a critical time

I fully agree with that statement...

 

[Glider]

I have to disagree. It is clear that the development of the radar as used by the British was researched, designed, built and used in operations by the British. To try and pretend that we used others peoples research and based our development is them is absurd, let alone 'ignored' patents. It may well be true that other people researched this and other areas but for whatever reason they didn't carry it through to a final working model. That wasn't the fault of the British it was the failure of other people or nations.

If you can substantiate this view I would really like to see it.

 

[parsifal]

not really, but honestly i dont think that theres much difference at all in what we are each saying. Im saying the Brits undertook research, which at that time was not secret....it was general research into wave theory (the patent issue aside....dont know that an idea can be patented anyway).... The British, along with everyone else would have had access to the international body of knowledge that everyone else had. The pioneering work was undertaken by the Germans and the Americans. There have even been claims the Russians invented the cavity magnetron (which Im not endorsing, just acknowledging). You can see the anti British sentiments flowing in some of those claims I admit, but Im not really in a position to refute them either. These more fantastic claims need to be treated with a certain suspicion, I admit. but what shouldnt be open to suspicion is that the Germans at least, in the mid 30's were better placed than Britain to exploit the science. They failed. i agree with your point on that, though you watch, there will be someone come along to claim that the Germans had the tech, butdecided for whatever obscure reason not to utilise it. i dont buy that at all. Centimetric radar was a fantastic, significant advnace, and it was led by Britain by 1940. they didnt "invent it" but they did develop it, and in war, development is more important than research.

 

[renegate326]

In 1886 when the German physicist Heinrich Rudolf Hertz discovered electromagnetic waves ,the race started . Germans and the Americans were in the forefront . German engineer Christian Hülsmeyer invents in 1904 "telemobiloscope" the first practical radar tested . 1921 the US-american physicist Albert Wallace
invents the magnetron as an efficient transmitting tube , in 1922 American electrical engineers Albert H. Taylor and Leo C. Young of the Naval Research Laboratory (USA) locate a wooden ship for the first time. in 1930 the American Lawrence A. Hyland (also of the Naval Research Laboratory), locates an aircraft for the first time.The first CXAM-1 antenna went to sea aboard USS Texas in 1938 the reason why the term radar entered the english language from the American .The German Hans Erich (Eric) Hollmann invents the cavity magnetron in 1935 ,filed a patent in 1936 long before the Brits and granted a patent in 1938 .. Yes , Randall and Boot improved it significantly and built a advanced version with more than 4 cavities in 1940 but they didn't invent anything ! they simply worked on and improved an existing technology.
Robert Watson Watt has invented a revolutionary application of the RADAR as early warning system. As far as I am concerned he was the one who saved Britain in 1940 and not the Spitfire or Rolls Royce Merlin engines

 

[Glider]

I don't quite know what you are trying to prove.
The first CXAM-1 antenna went to sea aboard USS Texas in 1938 and the first six units were delivered in 1940.

In 1938 the RN had the Type 79 surface to surface radar In Service 1938, please note in service not first aerial at sea
By 1940 they also had the ASV II, Type 279, Type 280, Type 281, Type 284, Type 286, all in service and action
The Beaufighter also entered service in late 1940 with AI radar.

The first true radar is accepted to be American when in Dec 1934 an aircraft was located and tracked at a distance of one mile. In June 1935 the British did a similar experiment but tracked the aircraft at a range of 17 miles. I will leave it to you to decide which was a more practical test.

I would suggest that the US achievements compared to the UK or even Germany at the time, didn't mount to a can of beans.

Re Randall and Boot improved it significantly and built a advanced version with more than 4 cavities in 1940 but they didn't invent anything ! they simply worked on and improved an existing technology. They didn't copy anyone as far as I can tell but it was similar to a German development in the early stages, they developed their own and it worked. If you can prove they copied an idea or developed an idea from the USA I will happily concede the point.

The other point is the magnetron. An early version was sent to the USA with the Tizard Mission and it should be noted that the power it developed was 6kw, the most powerful version the US had at the time was 10 watts. So again I will let you decide who copied who on this important point.

 

[parsifal]

I think his point is who undertook the research. And in this regard its getting pretty ridiculous. If we go back to the first stone age axe or the wheel, obviously they were precursors to airborne centimetric radar and not british inventions...... Then we move on to the publicly and more relevant investigations that so far are traced back to the 1890s. Why stop there, why not, for example look into the science pioneered by Faraday and others. the reason is because they dont serve the purpose this very partisan conversation is designed to do. The facts are, science is not national, it is international that crosses boundaries, and has done for hundreds of years. What isnt done internationally is the application of that research or science. and in this, it is irrefutable that in 1940 the british had taken radar and developed the science beyond what anyone else was doing. This is quite amazing and remarkable, because just 5 years earlier, the major strands of research were not british. they were german and apparently American. But neither the germans or the Americans developed the technology to a usable miltary weapon of any significance. the British did, and it was a lead I think they can rightly claim a clear lead in until the very late poart of the war.


When it comes to military secrets, givernments are keen to hold onto those secrets for as long as they can, but secrets do have a habit of becoming common knowledge sooner or later.

 

[Glider]

You certainly could be right but the tone and content of his postings makes me believe that he didn't want to give the UK any real credit for researching radar.

As for development I believe that the countries developing radar did it in parallel and almost inevitably there would have been similarities in some of the solutions.

 

[renegate326]

You certainly could be right but the tone and content of his postings makes me believe that he didn't want to give the UK any real credit for researching radar.

As for development I believe that the countries developing radar did it in parallel and almost inevitably there would have been similarities in some of the solutions.

You assumed correct I didn't want to give real credit . From 1865 when the Scottish physicist Maxwell presented his theory of the Electromagnetic Field until 1940 when Randall and Boot improved the effectiveness of multi cavity magnetron , all the game changing breakthroughs in BASIC RESEARCH incl. the invention of the cathod ray tube came from the US or Germany (not to forget the Italian inventor Marconi's ground breaking contribution) and all this is well documented . Whats wrong with my tone?

 

[Glider]

From 1865 when the Scottish physicist Maxwell presented his theory of the Electromagnetic Field until 1940 when Randall and Boot improved the effectiveness of multi cavity magnetron , all the game changing breakthroughs in BASIC RESEARCH incl. the invention of the cathod ray tube came from the US or Germany.

For content I rest my case, as for the tone, I let others make up their own mind.

If you want to go back to the first days of Cathode Rays I suggest you check up on J J Thompson an English physicist.

Development was international with varying degrees of co operation but turning Radar into a weapon of was started in the late 1920's and from about 1930 each country tended to keep their progress secret. How each country proceeded differed but to pretend that the UK copied anyone, a claim you have yet to substantiate, is far from the truth.

Your implication that the first CXAM-1 antenna first going to sea in 1938 on a US warship was some kind of breakthrough is of course totally wrong. The list of UK examples given clearly demonstrates that and those examples are easily checked with some research. It the use by you of that as an example which I didn't understand. If you could clarify your intention it would clear things up.

If you want to send me a PM to keep this from cluttering up the thread I am happy to supply details of books, web sites etc to help you look into this further.