Bismarck radar detector

[Bill Jurens]

I suppose, at the nub of it, lies the questions regarding how and why Bismarck was able to conclude that she was still being shadowed by -- i.e. was still being tracked by -- British units.

Although a good deal has, appropriately, revolved around the supposed interception or detection of radar signals from surrounding British units, I wonder whether Bismarck's assessment of the situation may have come one or more alternative sources, e.g. the interception of British radio transmissions, smoke, the perception of lights, or sounds interpreted as being from aircraft overhead or due to the noise of British screws, etc. These need not have been actually real to have been perceived as real, in somewhat the same way that Bismarck might have felt she was actually detecting incoming radar pulses, using some now indeterminate process, when actually she was not.

Does anyone have any commentary on these (perhaps rather far-fetched) possibilities?

Bill Jurens.

[wadinga]

Hello Bill,

i hope your appearance in he thread will get some interest and more general debate going . The "nub" is the specific content of Lutjens' UHR 07:27 message identifying the shadowers as two heavy cruisers and a battleship, when they were actually many tens of miles away and heading in the opposite direction.

Only a lookout's imaginary sighting in the morning could actually have classified the ships in the terms described, since the last time these ships had actually been seen was 12 hours previously. Propeller noises, smoke etc don't identify the vessels involved and describing the specific types instead of something more generalized eg "British units" is frankly inexplicable.

The excessive claims for he German GHG hydrophone system made by Brinkmann are nowhere backed up by other examples. This "wpnder system" cannot track Bismarck when she moves out of visibility range, gives no warning of the cruisers and is responsible for panics and alarums over imaginary torpedo attacks. Only with the development of sophisticated digital noise cancelling and filtering would surface ship passive sonar become really valuable, decades later.

If, and it is an if, Bismarck's B-Dienst team decoded the British signals that PG and SKL apparently did, Lutjens would have had positions and planned search directions for those particular cruisers and battleship showing they were nowhere near him, and moving in the wrong direction. HMS Victorious added to the information that no one was shadowing Bismarck when she transmitted her position and course westwards at 08:00B, 55 minutes before Lutjens' signal was actually transmitted.

It seems to me that a "Tinkerbelle Effect" has suggested to some who wish to reconcile Lutjens/AHS's actions with the lack of any actual evidence that there was shadowing, that a sophisticated radar frequency analysis has been carried out using some piece of equipment of which no actual trace has been found, which convinced them the same British ships were still "far-feeling" . I believe the excerpts from Raeder's extremely detailed report to Hitler and Fricke's to highest level personnel show there was no consideration that reception of radar was a factor because neither it nor a detector was mentioned. I cannot accept that because neither of these highest level officers in their Top Secret reports specifically stated that there was no detector, means there was one. Lack of evidence is not evidence. There are many things not mentioned, does that prove Bismarck had them all?

The 07:27 message and the "long-winded transmission" remain an enigma(!). The latter is written like a fully grammatical form of long, fully formed sentences unlike messages of the previous day which are concise, normal naval format. This long form message actually gives no information not already transmitted in the previous 18 hour, and thus serves no purpose. No wonder in the recent (dire) 24 hours to Doom documentary, a naval historian, Peter Hore says Lutjens suffferd from "verbal diarrhoea". As i have already I believe this is unfair, there are other considerations yet to be discovered.

All the best

wadinga

[hans zurbriggen]

Hello Mr. Jurens,
I agree with you: I had previously said that possibly a combination of detected radar signature, intercepted radio identifier (and/or messages wrongly interpreted) may have contributed to 07:00 situation signal. I tend to exclude smoke trails as weather was getting worse and even on May 24 morning with better visibility and ships forcing speed, smoke trails were visible from no more than 20- 25 sm (by PG and NF). Propeller noises were heard by PG from around 25-30 sm, so also them are not much probable at 07:00, when distance was almost surely more than 30 sm.
Clearly at 07:00 the situation convinced BS staff that the ship was still shadowed by the same 3 units.

Apart from this message, in his signal sent at 13:26 on May 24, Lütjens was already sure that British had radar equipments, not submitting to his command that this was only his conclusion (inferred by British shadowing) but as a mere fact. This is why I would tend to say that BS was equipped with a mean to detect enemy radar emissions (that Gruppe West asked to analyse). Its presence on board is confirmed by G.Hepke in his "radar war" (+ Brennecke, Baron and other authors too).

hans

[Bill Jurens]

Yes. I wonder if Lütjens had been informed -- perhaps only by highly-secret 'word of mouth' -- that German intelligence had revealed that British radars (including aircraft radars) were capable of a certain performance -- e.g. a detection range exceeding 30 nautical miles -- and further that it was reasonable to assume that that British units of some sort -- even though otherwise undetectable -- were almost certainly within this range band, that he was almost certainly being tracked by radar or something similar regardless of what the equipment he had -- or did not have --aboard was telling him.

Basically, he might have, correctly or otherwise, simply 'taken for granted' that the British were tracking him based upon speculative German assessments of British tracking capabilities...

Bill Jurens.

[wadinga]

Hello Bill and Hans,

I think, au contraire, it is Lutjens who by comparing erroneous reports of British shadowers' positions with his own dead reckoning errored position, who provides the gross overestimate of British radar performance. Raeder in his extensive report to Hitler, says it is a surprise but not an unexpected development to come across radar-equipped British ships. He falls short of saying it was so expected that he had arranged for a French company to start producing radar detectors more than six months previously, and ensured Bismarck had one, because he didn't and he makes no mention of radar detectors being available at all, except as future developments.

Raeder says http://www.kbismarck.com/raeder-berghof ... tml#annex1

An apparatus for the purpose of establishing whether one's own ship is being located by enemy radar has been completed and is now to be installed.

This is something which has only just been developed and and will be (future tense0 deployed.

We know what German intelligence estimates of British radar performance were because they are included in Feindliche Ortung http://www.kbismarck.com/funkspruch-flo ... tjens.html

It is the Baron's and in quotation Hans Henning von Schultz' opinion that all the British vessels were too far away for even one way signals to be received by Bismarck, even though they both erroneously believe detectors were aboard. HHvS was wrong about his own ship, and F.O. proves this, and undoubtedly misinformed the Baron, who readily admits to being no radar expert.

To break radio silence whilst attempting to escape just because one "took it for granted" that one was still being tracked would appear to be most remiss. Most commentators consider Lutjens signed his and his men's Death warrant by this action. A search for a rationale has produced a desire to believe in the radar pulse receipt theory which has been rendered invalid by F.O.and Raeder's report. Another explanation must prevail. Either Lutjens/AHS made an unwarranted assumption or there was another factor.

The radio signals decoded by B-Dienst are reproduced here

http://www.kbismarck.com/archives/telegram4.html

and are incapable of "misinterpretation" they show all the British vessels identified were many miles away and going further away, and with every hour that passed Bismarck was 20-30 miles further away from her pursuers. In the two hors between 07:00 and 08:55 when the erroneous report was actually transmitted Bismarck was 40-60 miles further away from the hunters.

All the best

wadinga

[hans zurbriggen]

Hello Mr. Wadinga,
re. 07:00 message, several contributing causes may exist to explain the wrong evaluation Lütjens staff gave of the situation, including detection of radar pulses, decryption of British units message identification codes and wrong interpretation of their content. British intercepted messages, as available here, are not relevant, as they were decoded by B-Dienst land based (or PG) team, not by BS on board team.

No 'future development' is already being implemented to all KM units few days (Raeder) or even less than one month (F.O.) later facts: passive radar receivers were already available for KM since 1940 . We know it from Mr. Saxton and from G.Hepke, who gives us a very good timing for German equipment development and deployment. Hepke is surely an expert: I am afraid you don't have any better source for deployment of German radars to counter his paper (except the mere avoidance to mention a secret device).
Lütjens message at 13:26 (already prepared at 08:01) on May 24 states that there were 'enemy radar equipments'. This is presented as a fact and not as a conclusion of Lütjens' staff based on British behaviour. The same is repeated (always as a fact) in other 2 messages including the long one, when Lütjens could have explained in detail the reasons of his conclusions. Therefore it is clear to me that BS had detected British radar emissions since May 24.

hans

[wadinga]

Hello Hans,

British intercepted messages, as available here, are not relevant, as they were decoded by B-Dienst land based (or PG) team, not by BS on board team.

This is an interesting assumption. Is there any actual evidence to back it up? Brinkmann complains the Flagship had a bigger and more effective B-Dienst team than his ship.

All the best

wadinga

[hans zurbriggen]

Hello Mr.Wadinga,
evidence: we don't have the documentation from Bismarck, thus we don't know which messages were actually decoded by BS B-Dienst team.
We know that BS had problems with her own transmitted messages. We can only assume that PG retransmitted to BS the ones decoded by her team (and viceversa) until separation: after that, we know nothing about British messages decoded on BS.
That's why I think also wrongly interpreted radio signals may have affected BS staff appreciation of May 25 07:00 situation.

hans

[wadinga]

Hello Hans,

So the only thing that indicates that Lutjens was not getting decodes of British lost contact reports is that he subsequently says in the UHR 07:27 that he is still being shadowed? That's not evidence, with respect, you have decided that because he transmitted, he can't have read the lost contact and position reports. That's just an assumption.

We can't assume that PG was supplying confirmation decodes because Brinkmann complains that his smaller B-Dienst team has to do the same amount of work as a larger team in Bismarck. This ability to read British codes should give Lutjens a huge advantage over his opponents, think of Midway, for instance. If he wasn't getting what PG or SKL was I expect the Flottenchef would make it happen by requesting it..

The previous day SKL were sending Lutjens their decodes for confirmation. Bismarck transmits shorter messages successfully in the early hours of the 25th, but at no time indicates problems for the onboard B-Dienst team. As late as UHR 01:29/25 Group West/SKL is giving details of interception and decode from British Unit 5DL. Surely if Lutjens realised he was missing vital British intel, he would ask them to keep sending him decodes. Notably, Group West/SKL does not send any of the lost contact decode results until after Lutjens has broken radio silence.

What we do know is that Bismarck had encoding problems and there was a send of the Enigma key in use: EGN. This does not suggest transmitter or receiver problems, the messages are unintelligible because of coding problems. This UHR 03:02, transmitted 03:42, is the last transmission from Bismarck for many hours until the transmission made at 08:55. Bismarck actually maintains radio silence for 5 hours, even PG hears nothing from her, during which time British radar signals, if they were being received at all by some presumed system, were getting weaker, and British wireless reports (even if they can't be decoded) are also getting weaker. Why bother to maintain radio silence for 5 hours if British radar and radio are being received? What changes at 07:00/25?

Then having maintained radio silence for 5 hours, travelling at 20 plus knots away from the last sighting of her pursuers, Bismarck suddenly starts transmitting at 08:55.

including the long one, when Lütjens could have explained in detail the reasons of his conclusions

He could indeed have explained the conclusions of any radar detector team aboard Bismarck, if one had actually existed, but in reality he says nothing about that. No indications of multiple sources, wavelengths, pulse repetitions rates etc. Remember Enigma is considered utterly impregnable, no need to hide this vital information. Nobody is hiding the extremely-secret fact that British codes are being read in real time by the B-Dienst. (Which is an appalling security gaffe in itself. One of the big "secrets"/scandals" still not being acknowledged, is that if the British were reading Enigma some days/weeks later, that knew their own codes were being read in real time, and did not change them.)

It's a shame Dave Saxton has not replied. He might explain whether in the light of the revelations from F.O and Rader's report, he still presumes there was a radar detector in Bismarck. He might say whether his information from Giessler predates the flat denial recorded by Kennedy. Herr Nilsson has not returned to explain whether Brennecke is actually confident that sure there was one, and crucially as a secondary source what his evidence is.

All the best

wadinga

[hans zurbriggen]

Hello Mr. Wadinga,
we know Bismarck had problems transmitting her own messages ('...it is assumed that the cause of the faulty transmission and reception conditions is influenced by the region of the sea south and west of Greenland - influence of the magnetic north pole -',
We can't know whether she had problems in receiving any message nor whether PG smaller team was more or less efficient than BS larger one.

In no one of his 3 messages re. British radars Lütjens said that this was his appreciation based on enemy moves, the fact was stated as a certainty.

hans

[wadinga]

Hello Hans,

The quote about messages Bismarck attempted to transmit refers to early on the 24th, and by the early hours of the 25th she was hundreds of miles away from this location. The only suggestion of radio problems early on the 25th are with encoding, which is why Bismarck sends the key she was using.

We can't know whether she had problems in receiving any message nor whether PG smaller team was more or less efficient than BS larger one.

Lutjens seems to have been quite demanding. If his B-Dienst team was incapable of doing what PG and SKL/Group West teams were doing and reading the enemy's communications, is it not likely he would have requested to be "kept in the loop" by the latter? There is no suggestion Lutjens was not reading British transmissions as were other German units.

Bill has suggested that we explore what imaginary British detecting systems Lutjens should have considered instead of opting for reporting the blindingly obvious one, radar. Bismarck was leaving an oil slick, but in rough seas and poor visibility this would be difficult to follow. The imaginary British hydrophone system that Brinkmann invented could only provide bearings as could infra-red sensors (which wouldn't work in snow/fog). Nothing about range from such systems. D/F ing Bismarck transmissions only works when the enemy is transmitting and only gives bearings, not range. There is no suggestion that the British had catapulted aircraft from the shadowers which were reporting the detail recorded in the Bismarck KTB at 0300/23

Intelligence duty reports demonstrate that the stalker correctly and rapidly detects course, course changes, and speed

Only a bearing and distance system, ie radar gives both to allow derivation of enemy speed relative to own . Lutjens applied Occam's Razor and reported radar, because it was the only sensible conclusion.

All the best

wadinga







.

[hans zurbriggen]

Hello Mr.Wadinga,
while we disagree about radar passive detector available on board BS (Lütjens was sure about British radar presence,already at 08:00 on May 24, and repeated it in 3 messages, not specifying it was 'intelligence' conclusion), radio problems were experienced on May 24. We don't know whether they had been solved or not on May 25: the reconstructed KTB is just based on what we know from land, from PG (before separation) and from survivors.

As said, I think that other factors may have given to Lütjens staff the impression that BS was still shadowed at 07:00, but the only probable ones, in addition to radar signature detections (most logical), are radio messages identifiers / content wrongly interpreted. I concur with you about the limited range of any other sensor and unavailability of other detection means.

hans

[HMSVF]

Evening.

Isn't this a case "we will never know one way or the other definitively"?


The bridge crew were killed so we will never really know what was what. I was listening to the recollections of HMS Repulse survivors during her sinking. Because a fair amount of bridge crew survived we have a pretty good idea of what was said and by whom and what the thinking was. Ditto HMS Prince of Wales at Kuantan. (recommend a listen - https://www.youtube.com/watch?v=3Qg7NIFvL34 )


We do have the Barons memoirs, but he is just one man. Unfortunately I just get the feeling that, like many things involving Bismarck and Hood, we are looking for Holy Grails that no longer exist (and may never have existed)


Just my musings of course.


Hope you are all well.


BW HMSVF

[RF]

As said, I think that other factors may have given to Lütjens staff the impression that BS was still shadowed at 07:00, but the only probable ones, in addition to radar signature detections (most logical), are radio messages identifiers / content wrongly interpreted. I concur with you about the limited range of any other sensor and unavailability of other detection means.

hans

There is another factor at play here, the fact that Bismarck remained at full action stations throughout the period which would impose a fatigue factor on the radio and radar personnel along with the rest of the crew, reducing their perception and efficiency.
We know that the radar ratings on HMS Suffolk were exhausted by the constant monitoring, one result of which is that when Bismarck turned 270 degrees to starboard to set course for the Bay of Biscay these ratings failed for some time to realise that radar contact had in fact been broken.

[wadinga]

Hello All,

Searching around the Naval Technology Forum I found a thread called German Radar in which Dave Saxton posted:

The Hipper's command was expecting their FuMB equipment to give them warning in such a scenario, and they had a false sense of security therefrom. Indeed on both German cruisers the Timor FuMB antenna was mounted opposite the foretop FuMO27 antenna on the foretop rangefinder.

There is an SKL document which analysis' the radar elements of this battle on the German side in detail. The Hipper's radar, the Luetzow's radar, IFF, and so forth. It states that Hipper's command reported that all enemy radar transmission intercepts with the FuMB equipment came from the South and none from the North. Why?

Burnett had taken the precaution of switching off his metric radars. The standard radar warning receivers such as the Metox and the Samos could detect transmissions down to a wavelength no lower than 60cm.

So on December 31st 1942 two major German warships seem to have inferior performance FuMB installations to that which Schepcke claims was installed in Bismarck in May 1941 and F.O. claims was to be installed in Lutzow. It would not be the first time a proposed but unachievable piece of equipment was promised but not delivered.

It would be interesting for the newest posters in the thread to give their opinions on the existence or otherwise of the "Holy Grail" based on the evidence presented including F.O. and Raeder's report. Short of two first hand independent descriptions from installers or operators we will never have definitive "proof". It will always be a balance of likelyhood.

Suffolk lost contact automatically on the outer leg because of her zig-zag course. When they zigged back in, Bismarck was nowhere to be found, because she had made such a radical manoeuvre. Ellis claimed it was his tiredness that failed to consider anything so unexpected. It is the business of officers to ensure their crews get some rest, so as to operate efficiently. Sometimes they forget that means them too.

All the best

wadinga