The radar technology race

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Christian VII.
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The radar technology race

Postby Christian VII. » Thu Aug 13, 2015 8:43 am

How close were the various countries really in terms of radar technology during the war?

The common story is that the Allies leapt far ahead once they started using the cavity magnetron and stayed ahead, but was this really the case?

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Dave Saxton
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Re: The radar technology race

Postby Dave Saxton » Thu Aug 13, 2015 3:12 pm

Regarding the cavity magnetron I posted this in another thread:

There is nothing special about the cavity magnetron in and of itself. Indeed the Japanese developed the cavity magnetron independently by the early 1940s but this did not translate into superior radar equipment. In fact the performance of Japanese Type 22 radar equipment was clearly inferior to that of both Allied and German radar equipment, particularly in terms of resolution, despite their cavity magnetron, and the use of centimetric wavelength.

The main advantage of the (strapped) cavity magnetron was the ability of it to produce centimetric or microwave radiation with power outputs of tens of kilowatts. The Japanese cavity magnetrons were not strapped and early European magnetrons were also not strapped. They produced outputs of less than about 5 kilowatts. Centimetric wave lengths create much higher antenna gain without needing to use large antennas. Antenna gain is essentially how focused and concentrated the beam is. Higher antenna gain provides two main advantages. First higher gain can (but not always) result in an automatic increase in range attainment. Secondly, it can produce a narrow beam while using a relatively small antenna. The result of a narrow beam is superior bearing resolution (not resolution for distance as that is a function of time parameters not frequency).


In terms of how tight the race was:

Early war the Germans held a monopoly on capable radar equipment at sea.

From 42 to 44 it depends.

Mk3, Type 274M, and FuMO27 were more or less equal in most performance parameters. Type 284M had the better bearing resolution (4.5*) and MK3 the worst (15* while lobing).

Type 271 was more or less equal to FuMO24 in surface search performance. SG-I was better because it used a PPI presentation. FuMO27 had the same range and bearing resolution as SG-I but did not use a PPI. Type 273P had greater range and finer resolution than SG but may or may not feature a PPI presentation. Type 273Q, if it used a PPI (not all did) had no equal in surface search performance circa 1943.

The Germans developed large antenna Seetakt models during 1943 to increase range. FuMO26 had essentially the same accuracy performance and range performance as Mk8.

Everybody ( except the Japanese) began to develop much higher output power by 1944. The British and the Germans both utilized spark gap modulation which produced hundreds of kilowatts of power. The US centimetric radars began to use high power pulser networks for radars like SG-II, SJ-II, SO...ect.... These new USN models were not as reliable. For example, US submarines found that the pulser networks of SJ-II, especially the pulse transformers, constantly broke down resulting in a rather unreliable radar. This was why the Germans and British developed spark gap modulation which was reliable. The British already had battled problems of pulser networks with Type 284/285M, and the Germans delayed the deployment of high output pulser networks for Seetakt because of similar problems in tests. Hohentwiel used a advanced helium thyratron and balum transformer, so it was a unique high power design.

During 1944 the British introduced Type 274, which proved incapable of spotting the fall of shot. Also the Admiralty Signal Establishment began to supersede Type 273 with Type 277/293 much to the displeasure of Fleet Command. Type 277 used a 3 d presentation called the Skyatron, but the actual radar performance was poor. At the same time the Germans began to introduce FuMO81 with multiple PPI presentation so we have a pretty tight race indeed, excluding the Japanese and the Italians.
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Re: The radar technology race

Postby dunmunro » Thu Aug 13, 2015 6:56 pm

in 1939-40 the KM deployed surface gunnery sets which could be used for short range surface warning as well. The RN deployed a handful of Type 79 WA (warning Air) sets that could detect aircraft at ~50-90nm.

By April 1940 the RN was deploying WA Type 279 and Type 280 that could provide long range air warning, short range air and surface gunnery functions and GCI (vector fighters onto approaching aircraft) for FAA carrier borne fighters.

By May 1941 the RN was deploying type 284 GS (dedicated surface fire control) radars along with type 285 GA (dedicated AA surface/gunnery) Type 282 (short range pom-pom AA ranging) and type 281 WA (combined long range air warning and medium range surface/air gunnery and surface search). Type 286 medium range WA with surface warning function was entering widespread use. The RN took the lead from the KM at this point and never relinquished it. The KM never matched the range of specialized and multipurpose radars that were increasingly deployed on RN ships from this time onward.
Last edited by dunmunro on Thu Aug 13, 2015 8:25 pm, edited 1 time in total.

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Re: The radar technology race

Postby Dave Saxton » Thu Aug 13, 2015 7:45 pm

dunmunro wrote: The RN took the lead from the KM at this point and never relinquished it.


In what ways? Range attainment? Accuracy? Resolution? I hope your not implying that Type 284/285, Type 281, or especially Type 286 was the equal of Seetakt in 1941. What RN "GS" radar could match FuMO26 and FuMO34 from 1944? How did Type 277 not relinquish the surface warning lead to FuMO81? What RN GA set could match FuMO213, or FuMO231, or Flakleit G?

in 1939-40 the KM deployed surface gunnery sets which could be used for short range surface warning as well


25km is not short range.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: The radar technology race

Postby dunmunro » Thu Aug 13, 2015 8:57 pm

Dave Saxton wrote:
dunmunro wrote: The RN took the lead from the KM at this point and never relinquished it.


In what ways? Range attainment? Accuracy? Resolution? I hope your not implying that Type 284/285, Type 281, or especially Type 286 was the equal of Seetakt in 1941. What RN "GS" radar could match FuMO26 and FuMO34 from 1944? How did Type 277 not relinquish the surface warning lead to FuMO81? What RN GA set could match FuMO213, or FuMO231, or Flakleit G?

in 1939-40 the KM deployed surface gunnery sets which could be used for short range surface warning as well


25km is not short range.


In another thread I stated:

I've been reading through Jacobsen. There's some very interesting info in it:

On page 34 he gives info on Scharnhorst's radar trials off Denmark's Bornholm island in January 1943; the forward set was able to detect a destroyer at 8 to 13.2km while the after set could detect the same at 10 to 12km.


This was similar to prototype Type 284 in Dec 1940 and similar to operational type 279 and probably inferior to operational type 281.

In any event, it is the whole radar suite carried rather than individual radar performance that really tells the story.

Also from a previous post:

DoY had a type 284M3 radar and used it in action in Dec 1943 and it included a highly accurate ranging panel, so we know that in 42-43 the type 284 could achieve better than 120yd accuracy:
DoY used a Type 284M(3) set at North Cape, in conjuction with both L12 (for splash spotting) and L18 (for ranging) panels. The L18 panel is described as a precision panel by it's designer C.A. Laws, so 284M did receive precision ranging panels despite the lack of the "P" suffix:

(6) "EMBODIMENT OF THE RANGING SYSTEM IN NAVAL
EQUIPMENT
The ranging system described has been incorporated in the
naval display panels LI3, LI7 and LI8, and has proved extremely reliable and consistent.
The overall accuracy depends
somewhat on the particular application but is in general a function
of three main factors. These are (1) error in crystal frequency,
(2) cyclic error of phase-shifter, and (3) setting error. The first
of these may be rendered negligible by a suitable choice of
crystal, the second has been shown to be less than 5 yd, and the
third, which depends (as in any system) on the nature of the
target, degree of fading, etc.; is usually less than 10 yd..."
A precision-ranging equipment using a crystal oscillator as a timing standard
Laws, C.A.
Electrical Engineers - Part IIIA: Radiolocation, Journal of the Institution of
Volume: 93 , Issue: 2
Digital Object Identifier: 10.1049/ji-3a-1.1946.0127
Publication Year: 1946 , Page(s): 423 - 440
IET JOURNALS & MAGAZINES



Of course DoY's type 273 also had a precision ranging panel and gave ~25 yd ranging accuracy but could not give high accuracy in bearing, IIRC.

DoY could spot 14in fall of shot up with the type 284m3 up to 20k yds and could use the Type 273 beyond that range, but as her type 273 had a PPI display Fraser preferred to use it to coordinate his forces.

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Re: The radar technology race

Postby Dave Saxton » Thu Aug 13, 2015 10:03 pm

In Jan 1938 trials conducted by Graf Spee established early model Seetakt's effective reliable range as 25km. On April 9th 1940 the Gniesenau's Seetakt set detected what turned out be Renown at 25km (27,400 yards) in nasty weather. In May 1940 early model Seetakt sets were superseded by models having four fold more power, upping the range to large surface ships by 20% more.
During the Bismarck chase in may 1941 Type 284 was able to track the battleship Bismarck to a max of 26,000 yards (23.7km) on occasion. More often it had to close to ~18,000 yards to reestablish contact with the battleship.

I can support a case that the RN took the lead in the surface search roles by 1942, however. Type 273 was an outstanding radar, and KGV got a PPI for its 273P by May 1942. But the late 1942 range performance of Type 273 to destroyers and cruisers was not that much better than FuMO27. Sheffield's Type 273P gained contact with the large Hipper at 19km (20,800 yards), and the German destroyers at much less. At the same time Hipper's FuMO27 sets could target enemy destroyers to at least 17.7km (19,400 yards). Luetzow targeted destroyers that day to 16+ Km, and spotted 6-inch shell splashes to 15+Km using its radar.

I can not support that RN never relinquished any lead it may have held in some aspects throughout the entire war. Type 284M certainly could not track destroyers to 30+km like the Prinz Eugen's FuMO26 did in 1944, and Scharnhorst was equipped with FuMO26 in 1943.

Average range accuracy of FuMO26 was 25 meters. What about the scatter of the timing of sending pulses introduced by Type 284M's pulser net work?

In any event, it is the whole radar suite carried rather than individual radar performance that really tells the story.


I do not agree with this opinion. In most cases only the surface search, and surface fire control, sets mattered outside of specialized carrier operations.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: The radar technology race

Postby Christian VII. » Sat Aug 15, 2015 7:17 am

I also think a little too much emphasis has been put on the cavity magnetron. It seems like it is all too often forgotten that this wasn't the only part of a radar, and that other important parts were developed during the war.

Btw, how far did the Japanese come in regards to using radar for their FCS? Did ever they reach the point of using it for range estimation? The Yamato features some rather largr arrays on either side of its main director for example.

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Re: The radar technology race

Postby Dave Saxton » Sat Aug 15, 2015 3:35 pm

Christian VII. wrote:I also think a little too much emphasis has been put on the cavity magnetron. It seems like it is all too often forgotten that this wasn't the only part of a radar, and that other important parts were developed during the war.

Btw, how far did the Japanese come in regards to using radar for their FCS? Did ever they reach the point of using it for range estimation? The Yamato features some rather largr arrays on either side of its main director for example.


Any radar can be used to measure range to target as long as it can detect the target at the given range. It doesn't have to be directly linked to the central fire control like most fire control radars were, to be used for ranging targets. A "primitive" radar is almost as good as a sophisticated fire control radar for that purpose.

The radar antennas you see on Yamato's director were Type 21. Type 21 was mainly used for air tracking but also could be used for surface search. Type 21 operated on 150 cm wavelength. Type 21 could rarely survive the blast effects of the 18-inch guns. Yamato had two Type 22 10 cm surface search sets, and a Type 13 air warning set as well.

The Type 22's were on the port and starboard sides of the foretop tower about 3/4 of the way up. They look like tiny dual fog horns. The bearing resolution for Type 22 was very poor because of the smallness of the antenna horns. Range resolution was probably poor because the pulse width was 5- 10 micro-seconds. The range accuracy was 100 meters, however. The range to target was anywhere from 25km BB to BB, to 35km BB to BB.

A dedicated fire control version of type 22, known as type 31, was under development from 43 to the end of the war. It featured three horns and lobe switching. It was never deployed aboard a warship.

Type 4X flak directing radars were also under development but never deployed before the end of the war.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: The radar technology race

Postby dunmunro » Sat Aug 15, 2015 7:30 pm

Dave Saxton wrote:In Jan 1938 trials conducted by Graf Spee established early model Seetakt's effective reliable range as 25km. On April 9th 1940 the Gniesenau's Seetakt set detected what turned out be Renown at 25km (27,400 yards) in nasty weather. In May 1940 early model Seetakt sets were superseded by models having four fold more power, upping the range to large surface ships by 20% more.
During the Bismarck chase in may 1941 Type 284 was able to track the battleship Bismarck to a max of 26,000 yards (23.7km) on occasion. More often it had to close to ~18,000 yards to reestablish contact with the battleship.

I can support a case that the RN took the lead in the surface search roles by 1942, however. Type 273 was an outstanding radar, and KGV got a PPI for its 273P by May 1942. But the late 1942 range performance of Type 273 to destroyers and cruisers was not that much better than FuMO27. Sheffield's Type 273P gained contact with the large Hipper at 19km (20,800 yards), and the German destroyers at much less. At the same time Hipper's FuMO27 sets could target enemy destroyers to at least 17.7km (19,400 yards). Luetzow targeted destroyers that day to 16+ Km, and spotted 6-inch shell splashes to 15+Km using its radar.

I can not support that RN never relinquished any lead it may have held in some aspects throughout the entire war. Type 284M certainly could not track destroyers to 30+km like the Prinz Eugen's FuMO26 did in 1944, and Scharnhorst was equipped with FuMO26 in 1943.

Average range accuracy of FuMO26 was 25 meters. What about the scatter of the timing of sending pulses introduced by Type 284M's pulser net work?



Gniesenau claimed detection at 0200 at 25km but her gunnery officer was sceptical, as false echos were common, and it seems, from the courses taken by the RN and KM forces that Renown could not have been anywhere near 25km from Gniesenau at 0200 (KM time) as it wasn't until 0459 that action commenced. Koop gives the range of Fumo22 as 14-18km. Edit: I see that Louis Brown states that another radar contact, at 25km, was made at 0450, which does fit the known courses.

Again, arguing that a particular KM set was superior to a particular RN set is misleading:

In any event, it is the whole radar suite carried rather than individual radar performance that really tells the story.


I do not agree with this opinion. In most cases only the surface search, and surface fire control, sets mattered outside of specialized carrier operations.


In May 1941 KGV carried a type 284 gunnery radar and a type 279 combined WA, GA, and GS set. These two sets complemented each other and gave KGV the ability to detect and track aircraft at ~90nm and the ability to simultaneously engage surface (via type 284) and air targets (via type 279) and to use type 279 as a back up to type 284 in the GS role. The two sets gave KGV radar superiority over Bismarck.

In August 1941, PoW reported the following:
19th - The PRINCE OF WALES re-commenced her working up exercises that had been interrupted by the BISMARCK break out and conveying Churchill to Newfoundland.
One of the priorities was the testing of the Type 273/M/P Surface Warning Radar of which the first example had been installed in the PRINCE OF WALES and was expected to have a range of 10 to 25 miles. A Mr S E A Landale from the Admiralty Signal Establishment at Haslemere came aboard for the sea trials. In the trials the set performed well and located the battlecruiser REPULSE at 19 miles, the light cruiser EURYALUS at 18 miles and the destroyer LIVELY at 14 miles.
The CinC Home Fleet was delighted with the results and wanted all Home Fleet ships fitted with the Type 273/M/P Radar, immediately.


In addition PoW had type 284 GS radar, Type 281 WA, WS, GA, GS radar, type 285 GA, Gs x 4 and type 282 GA x 4.

Type 284M certainly could not track destroyers to 30+km like the Prinz Eugen's FuMO26 did in 1944, and Scharnhorst was equipped with FuMO26 in 1943.


In Dec 1943 DoY's type 273 could track destroyers at ~30+ KM - again, DoY's radars complemented one another and you have to look at the whole radar package.

When was Scharnhorst fitted with Fumo26?

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Re: The radar technology race

Postby Dave Saxton » Sun Aug 16, 2015 4:14 am

Here are the historical facts of the range attainment development of early Seetakt:

• “Experiments during the summer of 1935 had shown that it was the unstable operation of the magnetron that prevented the expected maximum range of 20 km from being obtained consistently..”


• “ in the summer of 1936 the first transmitter with the newly developed TS1 decimeter wave triodes was ready…using the improved TS1 increased the maximum range for detecting the (400 ton research boat) Welle to 15km.. large steamers that passed were tracked to end of the 20 km range scale for which the set was calibrated for.. .”

• “In the course of 1936 the radar was improved and made more reliable…and the effective range rose to 25 km for a medium sized freighter. The arbitrary (range) scale for Seetakt was raised to 40 km.

• “In early 1938 GEMA delivered a Seetakt set for the pocket battleship Graf Spee…completing the experiences collected in the use of radar aboard ship with its installation aboard the Graf Spee proved useful. The location of targets in combat –simulation exercises was convincing. The high location on the hood of the optical rangefinder ensured effectiveness to 25 km..

• Helmut Giessler confirms that Renown was detected by radar at 25 km. He was there. Giessler has also informed that Seetakt worked well in close proximity to land, even within fjords.

• In May 1940 the early model Seetakt was superseded by a more powerful model we now call FuMO27. FuMO27 introduced the new TS6 triode. .. “The call of the Navy for increasing the range of their Seetakt sets for both surveillance and gun laying was more emphatic than that of the Luftwaffe. Their g-wave sets, which used grid modulated transmitters with two decimeter triodes of the type TS6, gave a maximum range of 30 km (to ships)…

Not only did FuMO27 bring a 30 km range attainment to Seetakt one year before the Bismarck chase, but it also featured advanced fine bearing equipment, and more accurate fine ranging system that was of more advanced design than the RN’s Precision Ranging Panels. Bismarck’s radar in 1941 completely outclassed KGV’s type 284 and 279 equipment. Type 284M only allowed the ASE to catch up to FuMO27. Even then the maximum range of Type 284M is listed as 26.5 km to a battleship.


It is interesting to compare the official specs of USN SG from 1945’s RAD THREE:

BB-35,000 yards (~32km)
CA-28,000 yards
DD-18,000 yards
Surfaced Submarine 9,000 yards
Periscope-2,000 yards
Large aircraft -20,000 yards

Judging from the range that Sheffield’s 273 detected Hipper it wasn’t much different circa 1942/43.

Scharnhorst received new FuMO26 sets in the fall of 1943.

I do not contest that Duke of York’s 273Q with PPI was excellent, but unfortunately it was soon replaced by Type 277/293.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: The radar technology race

Postby dunmunro » Sun Aug 16, 2015 9:32 am

It's strange that Scharnhorst didn't receive updated radar during her 1942 repairs while in Germany and it's hard to see when she could have received updated radar while in Norway.

DOY's Type 284M3 was able to range on Scharnhorst at 30.4k yds, despite the weather conditions.

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Re: The radar technology race

Postby Dave Saxton » Sun Aug 16, 2015 5:38 pm

dunmunro wrote:It's strange that Scharnhorst didn't receive updated radar during her 1942 repairs while in Germany and it's hard to see when she could have received updated radar while in Norway.
.


Documents read that Scharnhorst was equipped with FuMO26 while in Norway and that it carried out radar trials and radar directed blind fire gunnery exercises there. Some photographs of Scharnhorst in Norway I have seen also confirm this.
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