Was the Elektroboat really a "wonder weapon"?

[parsifal]

All agreed, but what isnt being considered are the improvements to sub weapons systems and silent running gear. Mark 48s had a range of about 50000 yards, whilst a sub launched sea skimming missile had a range of about 40-50 miles. Post WWII era subs were also far more difficult to detect because their acoustics were superior and because they could dive much deeper....typically to over 1000 feet. The equivalent of the Type XXI was the whiskey class diesel electric, and this boat was far more detectable than an Oberon or even an SSN.

Mulloka was a superior sonar designed to achieve a higher power output and cope better with inversion phenomenon.

In my opinion, whilst there had been great strides in undersea detection and attack systems 1950-70, there had also been great strides in submarine techs and weapon systems. My opinion is that relative to each other, submarines had widened the technology advantage, rather than lose ground. that is of course a value judgement, and open to alternative opinion.

 

[psteel]

I don't agree with your comparison between old and new relative capability. The newer systems had much better software search programmes and much better air component. I think helicopter dipping sonars revolutionized ASW missions.

http://www.uboataces.com/uboat-type-xxi.shtml

Whiskey was not comparable to the XXI, it was originally designed to counter the Type VII and was modified when Type XXI were captured . It could only manage 13 knots underwater .

STMMain

Project 651 Romeo/Julliet was a better comparion with XXI it could manage 17knots submerged and 300nm @ 3 knots. The Type XXI could manage 285 @ 6 knots and if Delycros reporting is accurate it was undetectable at that speed using the creep motors.

http://www.russianwarrior.com/STMMain.htm?1947vehicle_Whiskeyhist.htm1

 

[N4521U]

I think I've got the bends!

 

[parsifal]

Oberons have creep motors as well, and they certainly were detectable even whilst stationary. It simply is a matter from combat to combat as to how detectable your sub is, and no sub, however good it is technologically waas ever completely undetectable in all situation. For that matter no ship, of any description or nationality was ever unsinkable.

The earlier WWII sonars (eg type 144) are essentially as discriminating as those of the later Type 164s and 170s introduced 1950 and 1955, but simply with less power. What makes the problem difficult is the speed. Asdic wont work at speed, which means you need more escorts to track travelling at low speed, others positioning themselves to continue the tracking ahead of the sub, and others being directed onto the target to deliver the attacks. if the effective range of the Asdic is limited to 2500 yards as was the case with a type 144, you need more "stationary" trackers in your hunting group to maintain your search pattern. It doesnt mean the sub is undetectable. It means its more difficult to track and combat, and you need thickened up defences to beat it.

There is no such thing as an undetecbale target...at least no such thing that can have a blanket statement applied to it. There will be occasions when a sub is undetectable....thats what they rely on to deliver their attacks. Conversely ASW forces rely on detection to sink those subs. There is no such thing as a fullproof defence either, though that does not seem to be in contention here, since the germans were not manning the ASW forces.... They (the ASW forces) dont rely on detection to supress the target. If a sub is forced to submerge, it has a much harder task achieving a good firing solution. A submerged WWII sub, even a Type XXI is a relatively immobile target. Get him to submerge and you have the opportunity to re-route your convoy away from him. The problem with the Type XXI attack is that they could sustain high speed submerged for a relatively long time, but not indefinately, and not much greater than the speed of the a typical convoy. Suppressing a type XXI (ie forcing it to submerge and turn away) isnt as effective as it was against a type VII, but it was still effective, as it is against any conventional diesel electric boat. Only SSNs, with their relatively limiltless suibmerged speeds and power, can sustain a continual underwater attack .

The prize against conventional subs is of course to force the target to submerge in the first instance (thereby greatly increasing the survivability of your shipping because the sub loses its range and mobility advantages. In the second instance, the golden prize is to detect that submerged sub, achieve a firing solution and sink him. No submarine, at any time in history has ever been able to achieve that outcome every time. A type XXI as a piece of high tech kit was more likley than a Type VII, but not immune to detection and the density of the defences in 1945 would have meant its losses would still have been heavy.

To deliver an effective attack, a Type XXI equipped with unguided weaponary has to close to about 1000 yards to be effective. With a heavy amount of aircover, and the density of defences available to the allies in 1945, that a very tall ask. The germans hoped to counter that problem by attacking submerged using massed broadsides of Gnats. i have serious doubts that those tactics would have been all that effective. gnat was a weapon system more or less easily countered using towed arrays

I don't agree with your comparison between old and new relative capability. The newer systems had much better software search programmes and much better air component. I think helicopter dipping sonars revolutionized ASW missions.

You are making the same error again. What about the enhanced techs acquired by the submarine arm in that time. Sub detection and tracking systems exploded exponentially in the post war period, they also acquired weapons 10, 20 or 50 times as accuarate, and/or with greatly increased ranges. they acquired the ability to fired sub-launched SLAMs.

Whiskey was not comparable to the XXI, it was originally designed to counter the Type VII and was modified when Type XXI were captured . It could only manage 13 knots underwater .

I agree, but basing ideaas of overall capability on the basis of submerged speed alone is a poor way of determining the types overall capability. Speed is just one capability. The Ws could dive deeper, stay submerged longer and later had better weapons and electronics and detection gear fitted

The Type XXI was designed to have a design depth of 135 meters, which gives a crush depth of 340 meters and a maximum safe depth of 225 meters. However, when the finished product was tested, there was a minor problem in the design which reduced the design depth to 120 meters, so we get a crush depth of 300 meters and a maximum safe depth of 200 meters, rather similar to the VIIC. The deepest test dive was to 220 meters.

A W class had a design depth of over 200 meters, giving it a max design depth of about 350m. I do not know its maximum crush depth.

"During the five years following the end of World War II, Soviet exploitation of the Type XXI lagged significantly behind American fears. US intelligence initially foresaw in 1946 a force of 300 Soviet Type XXI equivalents by 1950. But it was not until 1949 that the first postwar Soviet submarine designs -- the Whiskey and the Zulu -- put to sea. While the Zulu was a true Type XXI, the Whiskey was a smaller, less capable, shorter range boat, designed more with an eye toward coastal defense and European littoral operations. It was not until the mid-1950s that Whiskeys were even given snorkels.

Early post-war construction focused on small submarines, the vast majority of which were Whiskey-class boats. Between 1949 and 1958 a total of 236 Whiskeys were commissioned. A shore targeting station would direct these vessels in their defense of the sea approaches to the Soviet Union. The larger Zulu-class and smaller Quebec-class submarines augmented the Whiskey-class. The thirty-two Zulu-class submarines operated further out at sea and coordinated with shore-based aircraft to provide targeting information to the shore centers. The approximately thirty Quebec-class submarines operated in the coastal waters.

During the 1950s there were efforts to convert Whiskeys into cruise missile submarines (SSGs). As the Soviet navy's mission expanded to combating the US Navy on the open ocean. The Echo I and Whiskey Long Bin class submarines deployed with anti-ship cruise missiles to fulfill this role."


They could dive

 

[psteel]

According to the site I linked the maximum safe depth of the Whiskey class was only 200m, which is similar to the XXI and was cleared in trails down to 220m before the war ended more testing. Likewise the endurance of the Whiskey underwater was not as good as XXI . Whiskey got 325nm@ 2knots while XXI got 285nm@ 6knots or 340nm @ 5knots. In other cases of German U-boats; if you half the speed from 4-2 knots, you almost double the endurance. Going on that; suggests XXI could be able to do about 590 @ 2.5knots [160 hours vs 230 hours].

Its quite clear from the samples Delcyros shared with us, the post war Destroyer Escorts had little or no chance of stopping modified American Guppy subs from attacking. These subs were less capable than the Type XXI in most respects [underwater speed and endurance plus quietness]. Given the ease with which they attacked, I would suggest your comparison is doubtful. I was reading a piece on NATO Canadian carrier ASW missions and it seemed even a single SSK Sub was a very difficult enemy to defeat in most of the exercises they conducted through the 1950s and 60s. Perhaps by the late 1970s Sonar technology and ASW surveillance in general, had improved dramatically? I suggest you read his piece.

 

[parsifal]

According to the site I linked the maximum safe depth of the Whiskey class was only 200m, which is similar to the XXI and was cleared in trails down to 220m before the war ended more testing.

You need to be careful when quoting max safe and max crush depth. The figures I relied upon for the Type XXI was the Uboat net site. plus i have a book at home. its max safe dive limit was 135 m, but due to some production issues (i dont know what, that was downrated to 120m. Max depth (ie with safety standards exceeded was 220 and crush depth slightly above that. The max depth they ever dived to was 225m. by comparison the W class has a max safe diving limit of 200m, which means they have a max dive limit of about 350m. I dont know the crush depth and as far as i know no western source has ever published one

Likewise the endurance of the Whiskey underwater was not as good as XXI . Whiskey got 325nm@ 2knots while XXI got 285nm@ 6knots or 340nm @ 5knots. In other cases of German U-boats; if you half the speed from 4-2 knots, you almost double the endurance. Going on that; suggests XXI could be able to do about 590 @ 2.5knots [160 hours vs 230 hours]

.


we would have to check, but it gets down to the power consumption and battery capacity

Its quite clear from the samples Delcyros shared with us, the post war Destroyer Escorts had little or no chance of stopping modified American Guppy subs from attacking. These subs were less capable than the Type XXI in most respects [underwater speed and endurance plus quietness].

Some of the old hands that trained with me had served postwar on Q and Battle classes. They used to comment on these American Guppy subs. They were considered very noisy and rather easy to track and sinkl to be blunt about it, so I am at a loss to reconcile my practical real world experience with the theoretical book learned values you aere relying on. Guess for you the theory carries more weight than the practice.

Given the ease with which they attacked, I would suggest your comparison is doubtful. I was reading a piece on NATO Canadian carrier ASW missions and it seemed even a single SSK Sub was a very difficult enemy to defeat in most of the exercises they conducted through the 1950s and 60s. Perhaps by the late 1970s Sonar technology and ASW surveillance in general, had improved dramatically? I suggest you read his piece.

As young PWO officers we could, and did train in the tactical warfare school at HMAS Watson using a very large computer simulation . The facility is called HMAS Watson and occupied an entire 9 storey building. At those training sessions we used it to train and simulate a wide range of tactical situations, using a variety of technologies from the early 50's through to the very latest at the time. This included using post war DDs to do combat with various subarine types. As trainees we would divide into PWO teams and be sdent to different rooms that were decked out as differnt ship types. I rember it was very cool being in submarines...you had a periscope that presented various targets and the like. Usually we trained with only RAN types loaded into the database, but we could and did simulate foreign types on occasion. That included USN Guppy types. For these older types we would usually load the older Darings and Battle class DDs of the 50s and 60s.

With carrier support, there was nothing special or unusual in hunting a Guppy. It was harder than finding a W or Z class boat, but much easier than finding an Oberon. We also sometimes trained as the attacking subs,and i can categorically tell you that it was never easy to deliver an attack against a defended target. nice story, completely at odds with my experience as a PWO.


I can only repeat, that with the passage of time, the scales tipped more in favour of the sub, not the other way around as you are repeatedly asserting. Things have gotten harder for the escorts with time, not easier.

After my experience with Del telling me the Bismarck was unsinkable, i will reserve my comments about his claims.

 

[delcyros]

Thanks Parsifal for sharing Your insights. From my perspective, operational ASW experience is a very important factor here, which lends credibility and weight to Your posts.

There are still a couple of issues, I´d like to outline, knowing that questions may be raised, which cannot be answered generally but they may be discussed to the one or other direction.

The question of applicability to XXI is likely not a straigthforward one. Sometimes it can be really difficult to detect, let alone intercept even world-war 2 Diesel boats with 1980´s ASW technology, referring to the attack carried out by an obsolete, ww2 buildt and equipped argentine Uboat in the Falkland war against HMS SHEFFIELD with a determined ASW screen. The torpedo attack was unsuccessful because the torpedoes were of 1940´s vintage technology. This would be in line with Your argument that a effectively guided stand off weapon is required for the XXI to be very successful against ASW.

The question whether or not such a weapon would be aviable to the XXI can be discussed on Rößler´s reference about german torpedo development, in my mind the most exhoustive study done to the subject with plenty of references to primary sources and written by a person, who was in touch with R&D and deployment of modern torpedoes in the post war german navy.

According to aviable sources, there were multiple guided torpedoes types developed in ww2. Not all of them can be considered successful. But in order to limit the discussion on feasable torpedo types and likely deploymental problems I will limit the response to few types.

In April 1945, XXI in service with operational flotilla 11, stationed in Bergen / Norway were equipped with an improved programmable and long range torpedo (LuT) with a straight running capability of ca. 8000m @ 40 kts on batteries. The programmable pattern allowed to shoot the torpedo independent from the submarine´s position and heading and down to a depth of 40m below the surface (OT-I). At target, the LuT could run pre-programmed patterns which would be very nasty in a convoi but help very little against escorts. Pattern sweeps also greatly limited the range of the device.
Also in service among type XXI and XXIII was an improved homing torpedo (T-Vb Zaunkönig II or Gnat in allied terminology). This torpedo was specified as an anti-escort homing torpedo with a range of 7000m at 27kts and better signal processing than the predecessor T-Va. The allied response to it would likely be a new type Foxer been slipped by the escorts. Foxer were responsible for ca. 15% T-Va failures in a post war study. Most of the homig torpedoes failed by either early or end detonation or detonation within the wake of the target according to a post war evaluation report (roughly 60%).
Not included at Bergen were wire guided or active homing torpedoes. These do exist and are referred to as "Geier" (active sonar homing) or "Lerche" (wire guided, passive homing), passing the german navy acceptance trials to february 1945. Production of these torpedoes was started at wars end. It appears to be improbable that much or any of these torpedoes would have been issued to submarines before july 1945.

With regard to the Whiskey class, the soviet´s themselve didn´t considered their Diesel-electric Whiskey class as a full aequivalent to the XXI in russian sources. The aequivalent was to be the ZULU-class in performance, though even the ZULU´s were not nearly as silent, particularely while snorting at periscope depth. The reason for the difference was a difference in perception of sound insulation persistent because of the soviet choice of sound detection gears. The soviets considered much of the care of the XXI sound insulation (f.e. the hydraulic drive and clutch, which dampens the sound of the main motors, rubber pads between structures and virtually all mechanical equipments) as complicated and excessive because they very late attained the knowledge that low frequency noise allows longer detection ranges in the open ocean than high or medium frequency noise in littoral waters of the Black Sea and Baltic.
I have some data for db noise vs speed for german XXIII (very little) and XXI (good sample) but little to compare that with except for the GUPPY boats which were compared in trials off Key West with U-2513 in 1946 and then again in 1948 with GUPPY´s. The immediate post ww2 noise discimination limit for wet immobile platforms using the HE-effect on the instruments employed in these trials was 70db. The XXI could be not be heard at 3kts and barely be heard at 5 kts on it´s main motors by an immobile listening platform and it´s signature was entirely lost in background noise when running on it´s creep motors even as close as 200 yards away with 6.2 kts (the maximum speed U-2513 could run on creep engines). A fleet boat could be heard at 2 kts, a GUPPY at 3 kts in compared conditions.
The HE data for U-2513 are those:



perhaps Parsifal can comment on those data.

 

[delcyros]

The prize against conventional subs is of course to force the target to submerge in the first instance (thereby greatly increasing the survivability of your shipping because the sub loses its range and mobility advantages. In the second instance, the golden prize is to detect that submerged sub, achieve a firing solution and sink him. No submarine, at any time in history has ever been able to achieve that outcome every time. A type XXI as a piece of high tech kit was more likley than a Type VII, but not immune to detection and the density of the defences in 1945 would have meant its losses would still have been heavy.

To deliver an effective attack, a Type XXI equipped with unguided weaponary has to close to about 1000 yards to be effective. With a heavy amount of aircover, and the density of defences available to the allies in 1945, that a very tall ask. The germans hoped to counter that problem by attacking submerged using massed broadsides of Gnats. i have serious doubts that those tactics would have been all that effective. gnat was a weapon system more or less easily countered using towed arrays

I agree mostly. One of the limitations of type 144 ASDIC (note, type 144 represents not standart ASDIC gear but the very final evolution developed in ww2 and served afterwards, similar to the XXI developmental timeframe) is accuracy of depth. Late ww2 ASDIC was not mounted on a stabilized platform and generally was incapable of accurate depth determination and failed at depths larger than 400ft. Type 144 gave serious improvements though still wasn´t stabilized,resulting in problems at depth determination and detection at depths larger than 800ft. That beeing said, 800ft is among the maximum XXI could operate with a reasonable tolerance to hull failure (it´s below testing depth and close to crush depth which was 304m in US water presure cassion tests and 285m in british tests).

However, with regard to the Gnat as a method of firing massed salvo´s I disagree. The Gnat wasn´t intended for that purpose. Massed salvos were to be fired with LuT pattern running torpedoes against convoi, not with Gnat. At least according to the operational instructions type XXI issued by the KM. I am also convinced that the efficiency of GNAT is often overemphasized in the literature. It´s a credible anti-escort homing torpedo (and in that functio can mess up even the most careful search patterns when the escorts are forced to step aside) but other than that it´s functionlity is limited.

To understand the issues involved here, one need to discuss or at least comprehend the problems for attacker and defender of a convoi.

For the escorts, the success is not necessarely to sink an XXI, it´s enough to deter the Uboat from intercepting and attacking the convoi.
For the submarine, the problem is that it will be limited on battery endurance during the approach or-alternatively, a vely long distance needs to be kept while snorting. Older boats lost their strategic deterrence when forced to submerge due to the fact that the one hour endurance at 6 kts with maybe 7kts top speed wasn´t nearly enough to enage a convoi unless it is detected within a narrow fan of the boats course and on convergent courses.
The US operational research group Report No-51 (1946) "ASW IN WORLD WAR II" goes into some details explaining the variables here.

An interesting function given there is the ability to attack dependent on the varyables of speed, endurance and angle to convoi. XXI are credited with a submerged endurance of 11 hours at 10 kts. originally, the boat was designed with an intended endurance of 1 hour at 18kts, though issues in hull and propellor design and in particular problems created by high current power in the batteries ensured that the XXI couldn´t achieve 18kts top speed and the endurance with full batteries was limited to 1 hour 20 minutes at 16kts rather than the tehoretical 1 hour and 40 minutes. Still, it had excessive endurance for lower speeds, particularely lower than 14kts, when the high current drop in battery output ceased to be an issue.

HC-convois had about 9.5 kts cruise speed, there were faster convois with 12 to 14 kts and slower ones proceeding with only 7kts. For an old boat, which could sustain only 4 kts for an hour or two this meant that the boat needs to be positioned within a fan of 64 deg along the convois heading when fist detected to make the intercept possible. Additionally, the detection range needs to be fairly small (8 to 6nm) to ensure that the boat can attain an atacking position before the batteries are depleted.
XXI boats would have more tactical ellbow-space. With 80% battery capacity, they could still run 6 hours submerged on 10 kts while maintening a reserve capacity larger than 2 hours at this speed. Thus, they could be positioned anywhere in a fan 185 deg wide along the convoi´s heading. Spaced 20nm away, 92 deg abeam to the convoi an XXI would find itselfe in a possible position, which may trigger an intercept attempt. This capability is important in my mind, because it allowed the Uboats to regain their strategic dangerousness, which the old boats completely were deprived off, due to their limited mobility and endurance operating submerged.

 

[davebender]

Type XXI submarines were designed to be quiet underwater with a streamlined hull and special silent running electric motors for normal cruising. In theory that should have made them quite a bit quieter then converted Guppy boats.

 

[parsifal]

Quoting and relying on published noise figures is problematic at the best of times. The RANs experience with its new Collins class ( a derivative of the type 471 class) is a good illustration. As designed, and in theory these ships had noise signatures about half that of the Oberons they were meant to replace. The noise made by the Collins class submarines was in fact problematic and unforeseen, which compromised their ability to stay hidden, and turned out to be a major problem with the design that took years to resolve (eventually it was resolved but it took some time). In the original requisition, the RAN guidelines for the noise signature of the new submarines were vague; for example, asking that they be "twice as quiet" as the Oberons. Expectations and operational requirements also changed between the 1987 contract signing and when the submarines began operating in the late 1990s. The major element of the noise signature for the Oberon class was machinery noise transmitted through the hull; this was successfully avoided during construction of the Collins class by mounting machinery on platforms isolated from the hull.

However, further noise testing during 1996 and 1997 found that the hydrodynamic noise signature—the noise made by a submarine passing through the water—was excessive, particularly at high speed. The shape of the hull was the main cause: although a scale model of the design had been tested during the funded study and was found to have a minimal signature, the hull shape was changed after the contract was signed, primarily by a 2-metre (6.6 ft) lengthening of the submarine and a redesign of the bow dome to accommodate the larger-than-expected main sonar and reduce its blind spot (the baffles). The design had not been retested, as who would pay for this could not be agreed on. Propeller cavitation, caused by water flow over control surfaces onto the enlarged blue ocean props at certain speeds was the other main noisemaker. Cavitation had not been a problem with earlier Swedish submarine designs or during early testing of the Type 471 design, but the propeller had to be redesigned late in the process to provide more power so as to cope with blue water conditions , and like the redesigned hull, was not retested. Subsequent studies by the Defence Science and Technology Organisation showed that the submarine's hull shape, particularly the redesigned sonar dome, the fin, and the rear of the submarine, focused the displaced water into two turbulent streams; when the seven propeller blades hit these streams, the propeller's vibration was increased, causing cavitation. After delays measured in years these problems were fixed by modifying the casing of the submarine with fibreglass fairings.

For a pretty good summary of the noise signatures of the Oberon class, I would rely on a Canadian study , with the following links provided. Oberons were developed from the Type XXI, at least in concept, and from my reading were "250% quieter" (whatever that means). Whatever the precise meaning of that statement, it must surely be conceded that oberons would be much quieter than the type XXI. According to the Canadians, Oberons have a noise signature under the conditions they specified in their 1994 evaluations of around 20-40 mhz at creeping speeds. That appears to be louder than those US test you have quoted (though I admit I may be misunderstanding the data you are presenting. The canadian evaluations are however consistent with the noise signatures I have seen for the Collins class, which noise signatures of less than 10 mhz at creep speeds.

http://pubs.drdc.gc.ca/PDFS/unc107/p534367_A1b.pdf

The upshot of all this, is however that you cannot assume that "oils are oils" from just one study. On the basis of that USN post war study, that appears to make the Type XXIs even quieter than the Type 471s, a design more than 40 years younger. Clearly something is wrong. Either the two studies are not comparable ( a very likely conclusion) or the US studies are not accurate. I discount the chances the Canadian and australian trials results are innaccurate, since they tend to reinforce each other.

 

[psteel]

While we are required to bow to your experiences they don't apply to WW-II experiences and therefor may not be of as much use. Worse some of us have referenced to submariners who say differently. Whos right whos wrong? Not my place to say.

Unfortunately it doesn't matter what we believe it only matters what we can prove. If we are relying on canadian results we are in trouble.


Report No-51 (1946) "ASW IN WORLD WAR II"

Covers allot of things. It mostly showed the huge gap between theoretical expected performance and actual battle results.

It showed the theoretical effectiveness of a ballistic ASW weapon was rarely ever reached in actual battle in fact taking years of combat to approach this value.
It shows that the faster the U-boat the harder it is to be targeted using ballistic ASW weapons which included Squid and probably applies to Limbo as well. The faster the U-boat went the more the 'average error distance' increased which impacted accuracy.
It also showed that real war detections attempts were ½ to ¼ as effective as the training detections runs and attacks.



BTW looking at this site GUPPY on batteries this guy calculates it gets one hour at 13-14knots or 20 hours at about 6 knots.

Barrow Submariners Association

 

[parsifal]

Covers allot of things. It mostly showed the huge gap between theoretical expected performance and actual battle results

.

Iagree with ths statement and its context, however the conclusions you are drawing are faulty. The statement should apply equally to both submarine techs and ASW techs. it should be appliesd with even greater vigour for new and untried technolgies, like the tyoe XXI over proven techs, because new techs invariably will have unforeseen bugs and weaknesses

It showed the theoretical effectiveness of a ballistic ASW weapon was rarely ever reached in actual battle in fact taking years of combat to approach this value.

what value? theoretical and actual effectiveness also affects submarine techs just as badly

It shows that the faster the U-boat the harder it is to be targeted using ballistic ASW weapons which included Squid and probably applies to Limbo as well. The faster the U-boat went the more the 'average error distance' increased which impacted accuracy.[/QUOTE

This is one of those classic situations where a relatively minor problem is paraded as a panacea for a lot of other problems. high speed does indeed cause a significant and exponential drop in wepon accuracy. You might also add that high speed (by the tracking escort) also affects the performance of its sonar. From that it is tempting to argue that attacking at high speed will reduce the vulnerability of the sub. and in doing so you would be 100% incorrect. Travelling faster underwater greater increases the vulnerability of the sub, because its noise signature also goes up exponentially as speed increses. There are several reasons for that, including increased machienery noise, increased hydrostatic noise (noise from the hull passing through the water, noise from increased hull cavitation, and lastly increased noise from cavitiation from the props. This applies aas much today as it did in 1945....a sub that has been detected, is generally dead if it tries to cut and run. It has to use temperature and salinity layers, creeping tactics and silent running to evade its hunters....not running.

 

[Lucky13]

Very interesting stuff gentlemen!

 

[delcyros]

I have little time to spare (working on a different project right now), but let me add some data to the discussion.

Most and foremost, what do You understand under the term "wonder weapon", gentlemen? This term is so vague and misleading that in my perspective it requires at least a definition, otherwise people may start claiming different aspects without comprehension of the historical meaning of the term.

Davebender wrote:

Type XXI submarines were designed to be quiet underwater with a streamlined hull and special silent running electric motors for normal cruising. In theory that should have made them quite a bit quieter then converted Guppy boats.

Yes, this is likely correct. US postwar comparative studies at high frequencies (1946 trials with U-2513) and detailed low frequency trials 1948 suggest that the XXI boats comissioned for trial purposes were significantly quiter and less distinctive in their sounds at all speeds compared than the GUPPY converted Tench fleet boat against the instruments and in those specific trial conditions. The differences were considerable enough to trigger much work in quiting all equipment and propeller noises as much as possible in the TANG class. The US, by that period already went into low frequency buisness. The soviets didn´t, resulting in comparably noisy submarines well into the 60´s.

Parsifal wrote:

For a pretty good summary of the noise signatures of the Oberon class, I would rely on a Canadian study , with the following links provided. Oberons were developed from the Type XXI, at least in concept, and from my reading were "250% quieter" (whatever that means). Whatever the precise meaning of that statement, it must surely be conceded that oberons would be much quieter than the type XXI. According to the Canadians, Oberons have a noise signature under the conditions they specified in their 1994 evaluations of around 20-40 mhz at creeping speeds. That appears to be louder than those US test you have quoted (though I admit I may be misunderstanding the data you are presenting. The canadian evaluations are however consistent with the noise signatures I have seen for the Collins class, which noise signatures of less than 10 mhz at creep speeds.

The OBERON trial data You referred to are very interesting, thanks a lot for this contribution. I would also agree that the details of trial conditions likely would render the data incomparative. Still, these are primary source data and have their value. I know that the services differed in db-definition. In Soviet services, f.e. the measurement differed and required higher salinity than in US trials and a different signal strength, resulting in 27db in russian data beeing similar to 20 db under US definition. German sound taking data, differ, too (caused by the lower salinity of the Baltic Sea) but I admit I don´t know the british definitions.
But I´m curious, how did the british determined that the OBERON´s were 250% quiter than the XXI when they didn´t conducted any sound trials on either XXI or XXIII? The only dedicated sound trials conducted by the RN after ww2 with captured german boats were on two 1943 vintage type VIIC models, similar except for one having ALBERICH anti-ASDIC coating while the other hadn´t. These trials were in order to determine and quantify the possible effect of rubber coating. Without comparative data, I am inclined to guess that no qualitative asessement is possible between type XXI and OBERON class.
The few data aviable under identic trial conditions refer to U-2513 off Key West against a US fleet boat (Tench class) with rather high frequency listening devices prevalent in the late ww2 period and some detailed comparative studies between a GUPPY I and U-3008 (or it´s equipments, to be precise) in 1948 using a GHG low frequency unit (later BQR-2).

(...) The statement should apply equally to both submarine techs and ASW techs. it should be appliesd with even greater vigour for new and untried technolgies, like the tyoe XXI over proven techs, because new techs invariably will have unforeseen bugs and weaknesses

This is entirely found to be correct. The principal reason, in my mind, why the XXI wasn´t rushed into combat zone was the necessarity to work out or at least mediate it´s technical bugs and issues. The class reached operational status not before april 1945 and was in trial status as late as march. And that despite the fact that most components of type XXI -as opposed to entirely new propulsion plants of type XVII and XXVI- were based on already prooven technologies (Diesel electric, hydraulic gear, snorkel, GHG, S-device). Several of the unprooven ones (100m deep OT-II firing circuits for the tubes), SP-SUBROC and it´s aiming device, several decois were simply dropped or delayed in the pipeline rather than worked out.


I have also compiled endurance data for XXI and extracted them from the range/speed data in operational instructions type XXI.


Note that what I consider important here is the excess reserve battery capacity of the type. A GUPPY-II (1949)can sustain 14.5 kts at the one hour rating, a FOXTROT-class (1959) can sustain 14kts for even 2 hours and the XXI (1945) 14kts for 2 hours and 50 minutes. WHISKEY- and ZULU class are in between GUPPY and FOXTROT. Indeed, I was kind of surprised (to say the very least) to find the notion in XXI op. instr. that it is directly suggested to carry out an intercept as long as the remaining battery capacity at the time of firing the torpedoes is 20% or more. That appeared to be very low to me in the first view but then again, 20% remaining battery capacity would still allow many hours endurance in an XXI, similar to a GUPPY at 50-60% capacity. Of course, I could have looked into Friedman or Roberts, who outlined this excess battery capacity in their early works, too...

I have little data for other submarines but it appeared that the TANG class did 1 hour at 17.5 kts and 43 hours at 3.0kts. The high speed endurance is comparable to XXI (had it been able to achieve such a high speed) but the silent speed endurance is not more than one quarter of it. Admittently, the comparably low figure (43 hours) at ultra silent speed (3.0 kts for the TANG) compared to a Fleet boat is likely caused by the much increased hotal load for the much increased, powerful suites of electronic equipment carried aboard a TANG class Diesel-electric attacking submarine. Why the TANG hadn´t used economical and ultra quite creep engines, I didn´t understood. The XXI benefitted much by those in it´s endurance at this speed region. U-3507 conducted speed and endurance trials off Pillau in march 1945 with new and fully loaded batteries and had an endurance of 162 hours and 20 minutes at the power run required to attain 3.0 kts on creep motors (this long term trial was in port, range specified was 487nm).

 

[psteel]

.

This is one of those classic situations where a relatively minor problem is paraded as a panacea for a lot of other problems. high speed does indeed cause a significant and exponential drop in wepon accuracy. You might also add that high speed (by the tracking escort) also affects the performance of its sonar. From that it is tempting to argue that attacking at high speed will reduce the vulnerability of the sub. and in doing so you would be 100% incorrect. Travelling faster underwater greater increases the vulnerability of the sub, because its noise signature also goes up exponentially as speed increses. There are several reasons for that, including increased machienery noise, increased hydrostatic noise (noise from the hull passing through the water, noise from increased hull cavitation, and lastly increased noise from cavitiation from the props. This applies aas much today as it did in 1945....a sub that has been detected, is generally dead if it tries to cut and run. It has to use temperature and salinity layers, creeping tactics and silent running to evade its hunters....not running.

Yes thats all understood but unfortnately not relevant to the specific case of Type XXI usage in 1945/46. Passive sonar was not the allied strength. There passive sonars would not have made any difference . The increased noise signature would have made up for the reduced passive sonar effectiveness resulting in the same detection range. ASDIC was a better bet for the allies at that time.

The Allies gambled on active sonar and it would have taken years for them to reverse course.

This is why I'm respectfully suggesting your 1970s experience base, doesn't really translate well in to a end of WW-II situation. There was just too much different.

 

[psteel]

From what I've read about wunderwaffen , one can dump the blame on Hitler himself. Prior to Hitler taking control of the military in mid 1930s, there was a long term strategic plan in place to rebuild Germany to mount an mechanized preventative war against the European powers by the early 1940s. This envisaged sufficient stockpiled military supplies munitions to conduct 1 year of continuous fully mechanized warfare with a WW-I sized armed forces. In addition to this another year of resources needed to build the second years supplies munitions was to be stockpiled and by the third year the economy was to have reached 'total war mobilization' levels. In addition to superior doctrine superior armaments and new high tech innovations were planned to give German troops a decisive edge in battle.

When Hitler inquired as to the progress of this plan in the mid 1930s, he was informed that, at the rate things were going, the plan could not be ready before the mid 1940s. Hitler baulked at this and threw the plan out replacing it with his own ideas. These included NO STOCKPILING of anything. There would be no steps towards 'total war economy' since the war he envisaged would be over quickly. Hitler instead would cobble together a 'limited war' strategy based on his superior will power with Germany's superior race plus what treaties and agreements he could make, to fast track the entire rearmament program by the early 1940s.

When war came prematurely in 1939 Hitler was forced to chuck part of his plan and take the needed steps to build up the armaments needed for a limited war. All long term plans and armaments [including experimental] were shelved to reverse the economy into more basic armaments....but only for a short war to occupy Europe and Russia prior to turning west and dealing with the Brits and Americans. When all this fell apart in Russia in 1941, Hitler was forced again to reverse course and fast track total war economy. When that appeared to have failed by late wars, Hitler grasped at Wunderwaffen to save Germany and himself.


BTW Delycros , great post. You do seem to know your material.

 

[parsifal]

Yes thats all understood but unfortnately not relevant to the specific case of Type XXI usage in 1945/46. Passive sonar was not the allied strength. There passive sonars would not have made any difference . The increased noise signature would have made up for the reduced passive sonar effectiveness resulting in the same detection range. ASDIC was a better bet for the allies at that time.

Passive detection had predatyed ASDIC in WWI. It was a principal means of detection in WWI. Between the wars all the major nations with submarines developed passive systems. The principal weakness of these early passive systems was that the listening ship had to be stationary to use the gear. Whilst I am not a real expert on wartime submarine techs, I do know enough to know that British subs entered the war carrying two types of passive listening gear, and that this gear was used to hunt and sink a number of German ships. The Americans also used a similar capability in their Pacific subs, and mated passive underwater detection with both active sonars and surface radar. I believe the british did the same,and considerable resources wre poured into the development of passive detection systems, such that by wars end, detection whilst moving at slow speed was practised.

Passive systems were not fitted to Allied surface ships were not fitted, not because they were not available, as their usage in Allied subs clearly demonstrates, but simply because they were not needed. Allied escorts needed a weapon that was of maximum usage whilst underway, and really were unworried about giving their position away to a U-Boat. A U-Boat attacking a surface escort wasnt going to live that long anyway.

So your claim that Allied advances passive detection was not available or not effective is just not supported by the facts. Passive detection was used extensively by all allied submarine forces, and appears to have assisted in kills of enemy subs. if Active sonars were proving inneffective there is no reason to suggest that the allies would not fall back onto their WWI experience and use their 1945 techs in their ASW forces.

The Allies gambled on active sonar and it would have taken years for them to reverse course.

Err no, incorrect. The RN and the USN each developed at least two Passive systems that I have read about and used them operationally. There were at least two decated research establishments that I know of in Britiain dedicated to the purpose and at least a further one in the US. German development did lead the allied effort, but that a big stretch, to the point of misrepresentation, to say the allies had litle or no capability in the field. They had consiserable capability, and considerable manufacturing capability, as well as considerable operational experience using the type.

This is why I'm respectfully suggesting your 1970s experience base, doesn't really translate well in to a end of WW-II situation. There was just too much different.

No, I would put it to you that you dont want to recognise my practical experience because it interfers with your preconceived notions about what the Type XXI was capable of. And whilst i am using that experience, I am not relying on it. I am using it at a yardstick to demonstrate the surrealism in the arguments being submitted relating to the the alleged immunity of the Type XXI. Just so we are clear, the Type XXI would have been a tough opponent, but not undetectable and not unsinkable. it would have suffered heavy casualties given the thickness of the allied ASW defences if used operationally on an extensive basis. in the same way as the Tiger tank or the Bismarck, technical superiority would count for little in the face of Allied overall superiority of numbers and other key areas areas of technology and operations.

 

[psteel]

No one said they didn't have passive sonars , but its clear they invested most of the industry into ASDIC systems.

Most passive sonars of this period were only able to detect 'battery powered subs' at about 2-3km ; roughly the same as ASDIC, but as you may have read on ORG 51; there effectiveness was orders of magnitude less than ASDIC systems, since they were passive systems.

Against a 'diesel sub' such passive sonars would have double the detection range and effectiveness , but such sonars would only get these ranges if the searcher was drifting.

Such sonars would not have helped the allies much, in any anti Type XXI war. An ASDIC system could work up to 15-20 knots attack speed - but with reduced effective range- they were still more effective.

German passive sonars seem to have been much better, with detection ranges several times the above figures.

 

[delcyros]

Passive sound detection was invented through world war one as outlined by Parsifal and was practicised by the RN through ww2. The method of application was a unified active / passive sound detection device to be known as ASDIC developed in the interwar period. The passive detection part was by a mechanically steered hydrophone.

In comparison to german active sound detection ("Schallortung" or "S"-device) and passive detection systems the major difference of the allied sets was the choosen, rather high frequency range. The active element had a range depending on conditions of 1,500 yard to 3,000 yard with a 5 degrees bearing accuracy, the passive element often did not reach this range.

German passive detection gears typically consisted of an integrated arrey of multiple crystal hydrophones steered electronically (by field manifold manipulation, rather than by turning of the elements), a solution which doesn´t produce any noise. Also, the frequency isn´t in the Khz range but in the Hz range.
The loss of db transmission is not similar at every frequency. low frequency arreys, such as GHG operaing in the 20-6000Hz region suffer a 75db loss at 40km range and 500Hz, while operating in the 6Khz frequency would have lost 105db at this range, everything else equal. That has to do with absorbtion of sound in water, which is significantly lower at low frequencies, the continuous level of sound propagation, where only very little loss at range occurs in the requency range 50 Hz to 200 Hz. At higher frequencies than 200Hz, the loss of sound level equals 6 db for a doubling from 200Hz, f.e. So why did the german switched to low frequency ranges?
This had to do with the technical issues involved in arrey solutions. The electrical delay for phase shift compensation has only a low resolution at high frequencies. In order to attain a higher resolution, the designers turned to lower frequency ranges. Surprisingly, they found that the absorbtion of sound was much weaker in low freqency ranges, creating very substantial differences in detection ranges between allied and german sets. Indeed, the differences are significant. The active element ranged to 100hm (10,940 yard) with initially (1935) 1.5 degrees, later (mid ww2) 1 degrees mean bearing accuracy but down to 1/30 degrees at very high frequencies. Altough the range differed with sound conditions, the active S-device, working on medium frequencies of 1000 to 10000Hz, could range at 4,000 yard and less even under worse conditions sufficiently precise to be integrated in firecontroll targeting computing.
The low frequency GHG unit could detect at much extremer ranges, 30km to 300km, though such ranges varied widely (caused by bottom return effects, which were not fully understood in ww2) and were often found impractical and thus created much discomfort with the technology. Direct detection out to 20km was possible in the open Atlantic in most conditions with an accuracy much dependent on the choosen frequency (8 deg at 500Hz, 4 deg at 1000 Hz, 2 deg at 2000 Hz, 1 deg at 4000Hz and 0.7-0.8 deg at 6000Hz). Thus, the longer the range, the better the return of the low frequencies but the worse it´s accuracy.
Of course, one has to understand that sound strength is dependent on source and not equal at all frequencies. It interferes with background noises and is highly varyable. That beeing said, the differences in capabilities between active and passive german and allied set´s is a true one.

 

[delcyros]

I once more reiterate my question regarding the charackter of the term "Wonder weapon".

I try to understand what exactly is meant with the question. I will forward the following list (which doesn´t necessrely need to be understood as complete):

[+] An illusionary object or weapon to be developed in the far or near future. A paper project.
[+] A weapon / system developed and attributed "war decisive effect" or strategic effect by the propaganda
[+] A weapon / system developed but not exploited of mere advanced technical details, whiches effect is limited to the tactical level
[+] A weapon / system developed with mere interesting technical deteails with unquantified effect on tactical or strategic level
[+] something else?

The XXI submarine type in my opinion (I may be wrong) is not a paper project. It isn´t invulnerable, either. It definetly wouldn´t have delayed soviet advancing ground forces by a minute, f.e. Though according to several post war studies conducted by the allied, it had the very practical outlook to render all ASW efforts carefully developed to counter the Uboat thread useless:

[1] the adoption of the Snorkel rendered detection by air in the night impractical according to operational experiences
[2] the adoption of RAM coated snorkels (see U-3008 trials), rendered new not yet introduced radars like APS-20 very unlikely to attain radar fixes on a snorting boat at night. The ECM mast would give pre waring in most cases
[3] the adoption of "Kurier" burst messaging (420 ms message) rendered HF/DF unable to attain a fix on an U-boat, thus routing of convois away from Uboat concentration couldn´t rely anymore on data gathered by HF/DF.
[4] the adoption of higher submerged speed and endurance greatly augmented the intercept fan and range to a target while approaching submerged, rendering obsolete the previous tactic of pressing a boat under the surface to prevent it making an intercept
[5] the adoption of 6 tubes + rapid reload gear greatly enhanced offensive potential on target
[6] the adoption of quiting technology and creep engines not only enhanced endurance but also made detection by HE impossible with period allied listening devices when operating on creep motors ("silent" by period allied sound detection devices operating at their respective frequencies), thus unknowingly relying entirely on active sonar for the purpose of detection.
[7] the adoption of deep submergence depth exceeded the limit of operational depth of Mk24 FIDO and the detection depth of ww2 ASDIC and approached the detection limit of post ww2 type 144 ASDIC.
[8] active ASDIC detection didn´t worked at speeds higher than 12 kts or poor seastate.


ORG 51, f.e. considers an XXI about four times as effective as an old boat in the offense and about eight times as effective in the defense. I consider this qualitative interpretation interesting as it would allow to relate the number of boats in the North Atlantic required to disrupt convois.

In the final period of ww2, f.e. in average 39 Uboats were at sea each month. They accounted for an average of only nine merchant vessels sunk per month (=0.23 / Uboat / month) while in average 18.9 Uboats were sunk per month.
Thus, an average number of 50 XXI at Sea per month (requiring at least 100 XXI our of the 120 produced to be in operational status) would result in an appreciable statistic likelyhood of 46 merchant vessels sunk per month in average (this same period) for a mean of 13 XXI sunk per month. Kind of comparable to the period July 1942 to June 1943 which was achieved by twice the number of submarines at Sea. One should factor in that even those very heavy losses in merchant shipping were replaced, thus even larger numbers of Uboats are required to have a decisive effect.

Thus, in my opinion, general statements are misleading. This applies to both sides of the discussion. XXI isn´t completely immune to ASW, so it can´t be claimed that it would have defeated convois by it´s mere presence. Similarely, it would be difficult to sustain the idea that an appreciable number of them would have had no effect on convois or would have suffered very heavy casualties on hands of the ASW.

Strictly, my opinion, of course