SONAR in the ship

[Dave Saxton]

Thanks Marc,

150 hm=15,000 meters.
115 hm= 11,500 meters.
24 knots sustained = ~4445 meters progress in six minutes.

Most interesting. I'll try to look up Prager's account hopefully in the next few days. I expect it to be most helpful.

[Dave Saxton]

Prager devotes about 10 pages to the incident and cites a slew of documents from the KTB, to Departmental Reports, to the Board of Inquirey. The 15km radar detection 6* to Starboard is confirmed.

I did learn quite a bit more about the overall history of Luetzow's radar and sonar installations as well. While at Gotenhafen prior to its Norway deployment it received updated active radar (FuMO27), and a complete suite of passive radar warning detector devices (FuMB), such as Samos, Bali, Sumatra, and Timor. It also either recieved S-Geraete or an updated S-Geraete. They were unable to run a complete battery of trials because the weather was so bad, but eventually they completed some limited battle exercises and tests of the new equipment with U-boats, and Luftwaffe Torpedo Bombers.

The radar was mainly tested for its utility in helping the ship better defend itself against air attack. It was found that the radar could accurately hold and track, and target, fast, wave top high torpedo bombers to reliable range of 4,000 meters.

It was found that the S-Geraete could accurately locate submerged submarines to ranges of 3,000 meters, (although the speeds during the test were 15 knots).

GHG- GHG was installed at some point prior to 1942, but I don't exactly when, or if it had GHG in 1940. There are refrences to the occasional use of GHG during the Norway deployment.

Battle Exercises and tests with the Tirpitz battle group during the Norway deployment focused on radar and blind fire radar directed gunnery, as well as detection of enemy radar with the FuMB equipment.

The Passive detection equipment performed well during Barents Sea. The active radar performed quite well tactically, and especially well for fire direction, during the Barents Sea battle, but initial confusion by Capt. Stange about friend and foe caused him to hesitate at the critical moment.

Luetzow was first equipped with active Seetakt radar in Sept 1937 while at Vito Spain. The radar was extensively tested and experimented with in Spanish waters, using the British battle group centered around HMS Hood as the unknowing test objects. It was found that they could locate and track Hood in all weather, day or night. When the Hood engaged in long range gunnery exercises they used the radar to observe Hood's shells in flight and the fall of shot.

[wadinga]

Dave,

Thanks for all the additional information. I gather Prager's book is highly informative but hard to get hold of and available only in German. I wish I could get hold of a translation.

This is from http://www.deutschland-class.dk/deutsch ... _hist.html and looks like a direct quote from the KTB and matches K & S.

From 1540, 10 April 1940 Lützow sailed for Kiel for repairs and to fit out for the still-scheduled Atlantic commerce-raiding operation. Along the fjord she made stops to pick up and set down various passengers before releasing her two escorts, Mowe and Kondor, to assist their sister vessel Albatros, aground and sinking near Søstrene, at 2200. On entering the Skagerrak, the cruiser found a northeast wind Force 4, Sea State 3, on a clear starry night with exceptional visibility. Lützow was soon steering 117° at 24 kt, Thiele remarking in the War Diary that, as British submarines were known to be stationed along the Swedish coast, he proposed to give them ample sea room by "standing off a little to the west at high speed".

At 0020, 11 April 1940 Lützow passed the Skagen-Paternoster line on course 138°.
At 0120, 11 April 1940 Radar reports object astern at 6°, 1,5 km.
At 0126, 11 April 1940 Turned to port at 1,15 km. Nothing seen, no further radar contacts, starboard rudder to original bearing to get us through Skagen Narrows as soon as possible.

At 0129, 11 April 1940 Lützow still turning. Enormous shock astern. Torpedo track reported acute angle port side. Assume submarine attack.
At 0130, 11 April 1940 Lützow still turning, rudder jammed starboard 20°. Compartment 11 does not answer or obey engine telegraph. Reported to bridge, "Manual rudder room cannot be manned. Stern flooding, ship listing to port and gradually settling." I intend to steer by propellers, port astern, starboard forward, at 18 kt.

HM Submarine Spearfish had fired a fan of her last four torpedoes at Lutzow and obtained a single hit astern, knocking off both screws and the rudder and breaking the stern.

At 0220, 11 April 1940 0220: Signal to Group East: "My position is 233°, 10 nautical miles off Skagen. Am unmanoeuvrable, flooding held, both screws lost. Lützow situation: ship drifting broadside to sea at 2 kt SW towards Skagen. I hope to find a lee and calm waters in Aalback Bay. As the ship is visible from afar, further submarine attacks are to be expected. Boats made ready for lowering, all crew members wearing lifejackets, all lower decks evacuated with exception of damage control personnel. "B" turret has jettisoned all ammunition to help lighten the stern. All Flak guns closed up, sharp anti-submarine watch set."
At 0318, 11 April 1940 Sent off ObltzS V. in the motor cutter to Skagen to request tugs and escort vessels.
0305 - 0337, 11 April 1940 Signals from Group East, "Torpedo-boats Luchs, Seeadler, Jaguar, Falke, Mowe and Kondor, 17th UJ Flotilla, 2nd E-boat Flotilla and UJ 172 on way to assist."

The enquiry must have been interesting if the 15,000m detect is correct! "So Kapitan, with a damaged ship (Drobak Narrows), no escorts and close to an area where enemy submarines had sunk three packed troop transports in a well escorted convoy you sailed straight up to an unidentified contact at night so so it could torpedo you killing 15 of your crew. Not to mention leaving your vessel at the mercy of that enemy, and denying the service of your ship for at least a year."

This source says the S-Anlage was installed 18th November 1940.


Is the radar detector installation the 12th June 1941 deployment or the 1942 deployment?

All the best

wadinga

[Dave Saxton]

The 150hm (15,000 meter) detection range is the range in multiple primary documentation. 1.5km is incorrect and it is probably the result of an erroneous secondary interputation being replicated. I don't think there's any question about it. The 15km detection makes far more sense too. With Luetzow covering ~4445 meters in six minutes (24 knots) it works out that the range would be 11500 meters at the point were it lost contact relative to the comparitively slowly moving sub. It works.

Luetzow turned to port after it lost contact, but once no more contact could be obtained, the Luetzow began to return to it's original course. It was still in the proccess of returning to its original course when the torpedo struck.

The sub being detected 6* from astern at a distance of 1.5km just doesn't work. After six minutes the range would be on the order of around 6km, not 1150 meters.

The passive detection gear was already installed when Stange took command as I recall reading it. Tirpitz had the passive detection gear suite by late summer 1941.

[Herr Nilsson]

Sean, Dave,

I have almost forgotten that I have got the German edition of the Koop/Schmolke-book.
In the German edition it's "6° Schiffspeilung", "150 hm" and "115 hm". It seems to me there is once again a mistranslation in the English edition of one of their books.

[wadinga]

Dave and Marc,

OK if the German version of S&K says so, we have to assume the multiple primary sources are unchallenged. Somebody seems to have added the word astern just to confuse things.

As a calm night, sea clutter would be at a minimum, but 15,000m is good performance. Rereading the account it sounds like they nonchalently closed until 11,500m when they turned away to port, and just three minutes later they decided it was nothing to worry about, and turned back onto base course. BOOM!

If Spearfish had some reloads available and the opportunity to pick her approach against her immobilised, helpless victim, Lutzow would have been blown to bits, and her Kapitan would have had a reputation for sleepwalking into disaster to match that of D'Oly Hughes of the Glorious debacle. Newsreels showing Spearfish arriving home suggest the crew thought they had despatched their victim. If only they had hung about to check on Lutzow's health, they could have homed in a flotilla mate to finish the job, and the Nazi Navy would have lost another unit in the Norwegian campaign.

S-Anlage with a 3,000m range is also pretty spectacular as allied ADSICs seem to be average c. 2000yds under average conditions. Vorspung durch teknik again, or just the best ever performance recorded as if standard? See http://jproc.ca/sari/asd_et1.html for excellent description of ASDIC in real operations. On the other hand another piece of fantastic German technology didn't stop Lutzow running onto a rock when she did eventually get to Norway. http://www.deutschland-class.dk/deutsch ... _hist.html 3rd of July 1942 getting ready to go after PQ-17. Operation cancelled and back to Germany again for yet more repairs.

The comprehensive outfit of passive radar systems seems incredible for 12th June 1941, when just over a couple of weeks earlier, Bismarck has gone down with what seems to have been some kind of secret prototype (apparently incapable of reporting the frequencies in use against her as ordered), and Brinkmann was speculating whether such a system might even be possible. Can you confirm a 1941 installation? AFAIK Metox FuMB-1 was not issued to U boats until a year later, with a Heath-Robinson wooden aerial.

Can you give some more detail about the use of active and passive radar at the the Barents Sea fight? Hipper's KTB sighting report is said to be Mk 1 eyeball in Dudley Pope's 73 North not super Seetakt, and any number of Indonesian Islands didn't warn them them the approaching ships were British until a storm of 6"shells did.

Sorry to be such a doubting Thomas but I think it is really import to nail down real performance in action and not accept too easily the rose-tinted records of Trials in perhaps easy unrealistic conditions.

All the best

wadinga

[Dave Saxton]

I will have to double check the date of the FuMB installation when I get the Chance. Tirpitz was equipped with these devices by Autum 1941 though.

Radar detection range can be quite dynamic depending on a multitude of variables.


Pope doesn't address the issues of radar performance in much detail and really doesn't address the German side of the equation other than by assumption. After the Germans divided their force, Stange approached the battle arena by switching on his active radar for two minutes at ten minute intervals. The visibility was 300 meters early that morning. The FuMB devices began picking up British radar emissions at least an hour before it arrived within combat range of the British convoy, which was being turned toward the Luetzow group by Kummetz's hit and run tactics from the north whith the Hipper group, as was the battle plan. Stange was being careful not to give away his position by his own careless use of active radar. The Germans assumed that the British also had radar detection devices by this time as well. According to Howse, this was indeed the case.

After additional radar pulses were recieved by Luetzow with a signal strength of force 5, Stange ordered the Seetakt switched on for good. It quickly revealed the British convoy's positions, with individual steamers located at ranges from 16km to 11.4 km away from the Luetzow. The gunnery officers wanted Stange to attack with radar data alone, but Stange was too unsure of the identity of the targets. Adding to Stange's paralysis was the fact that radar pulses received had a PRF of 500 -the same as Seetakt (The British 286 sets also had 500 PRF, and the 285 and 284 sets had about 600 PRF) They could not be seen visually beyond just shadows and so could not be positively identified. Sending in the German destroyers may have just aggravated the uncertainty, so he kept them closely tethered.

After nearly 30 minutes had been allowed to elapse, the Lutzow's radar exchanged IFF signals with the Hipper's radar, which was located about 23km northwest of the Luetzow. Then Stange realized his error and reversed course intent on engaging the convoy which was now a min of 16.5km south west of the Luetzow's position.

At this time the Luetzow's Seetakt located two firm contacts approaching from the north at a range of 29km from it's own position. This was Sheffield and Jamaica. The British cruisers had located Hipper at a range of 23km from their own position with Type 273 radar, and were approaching the Hipper unseen from the north, while the Hipper was preoccupied with the task of hitting the Ashates from a range of more than 18km with radar directed fire. Stange considered the range too great to engage, and by then steamers could be seen and identified optically to the southwest, highlighted by the artic twilight on the southern horizion. The Luetzow opened fire, but after two salvoes the targets were completely shrouded again by snow squals. Luetzow however, continued to straddle the target by radar directed blind fire for the next six minutes. The radar operater reported the spotting the fall of shot was becoming rather difficult because of the radar indication "jumping" with every 28cm salvo. The radar was shut down to reset it (obviously a microphonic vacuum tube) bringing this espisode of fire to an end. The radar was back up and operating within 5 minutes, and the Luetzow was able to use it to damage the Obdurate from a range of 15,400 meters, and to also monitor the shadowing by the British cruisers after disengagement.

When the Hipper first engaged the British destroyers a couple hours earlier it would have surely of had to use radar because the visibility in the predawn darkness and the fog was only a few hundred meters. Kummutz recalled his destroyers so they would not become confused with the enemy. Hipper scored a first salvo hit on Ashates at that time from a range of 14km. I have been informed that the Hippers forward radar was possibly disabled at about this time frame with an electrical power failure, and so had to turn away repeatedly to bring its aft radar to bear. Kummetz wanted to do this anyway, because his object was to draw away the convoys escort to himself while turning the convoy toward the Luetzow group, which was he quite successful in doing. Nonetheless in episodial fire, Hipper badly damaged British destroyers while staying beyond range of effective torpedo attack.

Hipper was surprised by the British cruisers mainly because it was focused on the task of sinking the Ashates at the time, and because its detection gear could not detect Type 273, or possibily Type 284/5.

Tovey wrote in his report that the British radar other than Type 284, which performed well for gunnery ranging (according to Howse were not M models sets with lobing) did not perform all that well during the battle. Jamaica's 273 was knocked out by its own first salvo, and the sets on the destroyers could not locate and hold the German warships by themselves. The 286 sets proved useless and the 271 sets were only able to locate and track the Germans if "put on the target" by visual sighting, and then only to max range of 16,000 yards. The Allied IFF system in use failed completely.

[Panzerschiffe]

Thanks for the replies to my question about the Graff Spee possesing sonar and/or hydrophones. I found in Koops and Scmolke's Book "Pocket Battleships of the Deutschland Class" that S-Anlage was installed in the Lutzow in the refit after it was torpedoed by the Spearfish (page 53). In Krankces book about the Admiral Scheer, "Pocket Battleship", he refers to detecting a shoal of fish on their Asdic?

[Bgile]

Fish and especially marine mammals are the bane of sonar operators. They can make it difficult to listen and mask entire sectors because they can be quite noisy.

[wadinga]

Panzerschiffe,

Well spotted in Koop and Schmolke, I just looked in the Technical listing, you read the book Good Work!

On the Danish site http://www.scharnhorst-class.dk/gneisen ... ejuno.html shows pictures of Gneisenau's S-Anlage installation, four rectangular plates, on the forefoot, along with the retractable paravane spar, during damage repairs. I still can't see the elusive GHG installation. This may help find out about S-Anlage in Graf Spee. Doesn't appear to be there in launch pictures of GS but maybe she was dry-docked prior to sailing off on her last mission before war was declared.


Dave, Incredible detail about german radar at Barents Sea, are you able to divulge your sources?

The Spearfish attack on Lutzow. If this German account is correct this may be one of the longest successful torpedo runs in history.

it works out that the range would be 11500 meters at the point were it lost contact relative to the comparitively slowly moving sub. It works.

I'm not so sure it does work, if Lutzow gets hit only 3 minutes later, Spearfish must have launched the fish when the range was greater than 11.5kms!!!! The torpedo can only travel c.3km in 3 minutes.

I suspect the truth is somewhere between the two accounts.

All the best

wadinga

[Dave Saxton]

Dave, Incredible detail about german radar at Barents Sea, are you able to divulge your sources?

Particularly helpful is the West German Bundes Marine War College's 1983 indepth analysis of this battle based on both German and British primary records. The reconstructed battle map from this is incredible. It also records commentary from Adm Kranke, Adm Johanessen, and Adm Forster. For the Luetzow specific perspective Prager is once again very useful, and his account is actually a paraphrase of the Luetzow KTB. Howse includes completely Tovey's commentary on the British perfomance and his complaints about the British optical firecontrol and radar failures.

[RF]

Particularly helpful is the West German Bundes Marine War College's 1983 indepth analysis of this battle based on both German and British primary records. The reconstructed battle map from this is incredible. It also records commentary from Adm Kranke, Adm Johanessen, and Adm Forster.

Was there any involvement or comment from either Kummetz or Stange in this analysis?

[RF]

There is no mention of GHG assisting Scheer's commerce raiding campaign. I have not read of Graf Spee using GHG.
wadinga

Strictly speaking, in the case of the Scheer there would have been no need for it, convoy HX-84 was found without electronic aids.

On the other hand AGS might have had use for it on the morning of 13 December 1939 for the search for Highland Monarch - and presumably (if equipped, have picked up the noise from Harwoods' ships. From what I have read there is no mention of GHG.

[Dave Saxton]

Was there any involvement or comment from either Kummetz or Stange in this analysis?

Not directly, if recall correctly. Were they available in 1983? At any rate their entries into the KTBs and their de-breifings would have been a matter of record. Some of the commentary by Krancke and others, may have been recorded previously too.

[RF]

I asked because I believe that Stange served in the West German Navy post WW2, so something from him might have been recorded during that period.