What was wrong with the Magnetic torpedoes?

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HansvonLuck
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What was wrong with the Magnetic torpedoes?

Post by HansvonLuck » 06 Aug 2005 04:14

I'm reading about the first half of the U-boat war and it seems that German magnetic torpedoes were a complete failure and handicapped the U-boats during '39 and '40.

The Germans tried everything to "fix" the magnetic torpedoes especially desensitising it to reduce premature detonations.

It also seems that the Americans' magnetic torpedoes were ineffective by the time they came in the war.

So, I have 2 questions:

-What were the major problems with these magnetic torpedoes? What made them so defective and prone to premature explosions?
-Since my book only covers the first half of the U-Boat warfare, did a country develop a reliable magnetic torpedo by the end of the war?

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Uninen
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Post by Uninen » 06 Aug 2005 16:48

There was a electronic treatment for ships that was at least used by Brittish to counter German magnetic torpedoes that reduced the magnetic signature of the ships enough to make the magnetic fuzes fail.. I no longer remember the details, but maybe somebody else can help..

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spiro
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Post by spiro » 06 Aug 2005 17:17

I think i've read somewere that after firing one of these torpedoes,the Uboat should dive, cause it could also get hit. 8O

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Post by tommy303 » 08 Aug 2005 02:55

The problems with magnetic pistols in the various torpedos, British, German and American, had mainly to do with lack of understanding about the earth's magnetic fields--ie there were areas where magnetic anomalies tended to fox the pistols, triggering them as soon as the torpedo finished its arming run. In other cases, prematures occurred if the torpedo deviated from its course suddenly, as in an arial torpedo porpoising after hitting the water. Later on, the Germans, British and Americans went back to the drawing board and most had a decent magentic exploder in service by 1943/44.

Uninen,

I believe you are referring to the degaussing coils which altered a ship's magnetic field. Both the British and the Germans had these, not only for service against magnetic torpedos, but magnetic mines as well. Nominally, magnetic exploders were supposed to be sensitive enough to pick up a ship's magnetic field and fire the warhead at a point about 10 feet or more below the hull. The coils altered the field enough to cause a magnetic exploder to fail unless it were only 3 to 6 feet below the hull depending on the design of the exploder. This would cause a fair number of torpedos and mines to be duds if running deep or laid in deep waterways.

Spiro,

I think you might be referring to the acoustic torpedos fielded by the Germans. These moved at a set depth, but could alter course looking for the loudest propellor or machinery noise. Occasionally, such a torpedo might chose its parent sub as the loudest noise in the neighborhood and go after it instead of the intended target, so it was a wise move to go to a deeper depth after firing one.

thomas

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Tim Smith
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Post by Tim Smith » 09 Aug 2005 16:14

German torpedoes did not have just one problem, but several.

1. The magnetic detonator was unreliablie, especially in the far north, due to being too sensitive the Earth's natural magnetic field. (Torpedo magnetic detector detects the Earth, thinks "Oooh, what a big ship I've found!" and explodes. Boom.)

2. The contact (impact) detonator was unreliable. It would often not explode which impacting a ship's hull at an acute angle (significantly greater or less than 90 degrees). So the Germans had to set up a 90 degree perfect shot to get good results. Often that was no possible to do. If they didn't, the torpedo would hit the target's hull, bounce off with a clang, and sink to the bottom of the sea.

(Note: The Americans had the opposite problem - their torpedoes DIDN'T explode at 90 degrees, only at an angle to the target's hull. So the more perfect the shot, the less likely the torpedo would explode.)

3. The torpedoes occasionally detonated prematurely, usually when arming themselves. Torpedoes would not be launched armed, due to the danger to the firing U-boat. A little propellor on the front of the torpedo would spin as the torpedo sped through the water, and once it had spun round enough times (500 yards from the U-boat) the torpedo would arm. But sometimes the torpedo would detonate as soon as it was armed. (Torpedo thinks "Oooh, now I'm armed, it must be time to explode!" Boom.)

4. The torpedoes ran at the wrong depth, usually deeper than the depth set. So they ran underneath the target instead of into it. And if the magnetic detonator wasn't working, the torpedo would not explode. This problem was caused by the torpedo depth running equipment not being airtight. It needed to be airtight because it worked on air pressure to control depth. Now when a U-boat fires a torpedo, the high-pressure air used to propel the torpedo out of the tube is vented into the boat. (Venting it out of the boat would cause a huge mass of air bubbles to reach the sea surface, revealing the position of the U-boat to the enemy.) So the air pressure inside the U-boat would rise dramatically, and that would affect the depth control equipment of the torpedoes still unloaded. Also air pressure in a U-boat would rise dramatically if it stayed submerged for a long period.

5. The torpedoes, if they missed the target, often blew themselves up when they reached the end of their run (used up all their battery power). This also gives away the presence of the U-boat to the enemy. (Torpedo thinks "Damn, I've missed. So I'm going to blow myself up in shame." Boom.)


So you can see the Germans had a lot of problems to solve with their torpedoes. It's amazing they sank anything at all in 1939-40.

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Post by gabriel pagliarani » 10 Aug 2005 15:24

Tim Smith wrote:....1. The magnetic detonator was unreliablie, especially in the far north, due to being too sensitive the Earth's natural magnetic field. (Torpedo magnetic detector detects the Earth, thinks "Oooh, what a big ship I've found!" and explodes. Boom.)....
Effectively the real "shape" of the Earth's magnetic field (equipotential field of magnetic force wich surfaces dive into Magnetic Poles, very similar to the layers of a a big onion centered in the core of Earth) were discovered by Van Allen in 1957 after the launch of Explorer-1, the 1st western artificial satellite.. I think that at very today there must be a lot of problems with magnetic driven weapons if tested very close to magnetic poles.

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Post by HansvonLuck » 10 Aug 2005 20:23

Thanks all...
I've kinda "guessed" it would be the Earth's magnetic field since the U-boat didn't manage to sink anything (except a very few) during the Norway Campaign.

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Post by gabriel pagliarani » 11 Aug 2005 08:00

...but this fine argument could not be closed so easily. The magnetic field produced by the iron-nickel melt core of Earth change direction of magnetic flux by changing latitude. It can easily change the direction of the H.V. electronic beam driven into commercial and not-shielded cathodic tubes (TV & RADAR displaies) and thermoionic valves (well known as "octopodes") largely used before the birth of solid-state transistors in any amplifier device. If you buy a CRT computer monitor or a low cost TV in Scotland or Finland then you carry it in Sicily, you will test a general lowering of the quality of the show. This fact is due to the trimming of the degaussing device locked to the tube: the iron grid ( driving anode) embedded in it works differently by changing latitude. Buy only your national-trimmed CRT device, there is nothing nationalistic in doing so.

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Post by Karl » 11 Aug 2005 08:35

gabriel pagliarani wrote:... This fact is due to the trimming of the degaussing device locked to the tube: the iron grid ( driving anode) embedded in it works differently by changing latitude. Buy only your national-trimmed CRT device, there is nothing nationalistic in doing so.
Ahaaaaa-haaaaa!

Is that really true or are you a TV salesman?

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Post by Von Schadewald » 11 Aug 2005 15:15

U 377 & U 972 were both lost when homed into by their own Zaukonig torpedoes.

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Post by gabriel pagliarani » 11 Aug 2005 15:26

Karl wrote: Ahaaaaa-haaaaa!
Is that really true or are you a TV salesman?
:lol: ...no current business in domestic appliances, unfortunately. But it is true: try to read "Scientific American" issued last february. The argument was the new super-cheap flat-CRT computer monitors forecoming: a lot of money was spent in looking for a new self-trimming device able to avoid the problem of latitude-adjusting. This was the reason why SAC of USAAF urgently developed plasma-displaies during'60s: the RADARS onboard their B-52H streaming the skies over North Pole while waiting the ultimate call for Armageddon against SU required urgently a more reliable monitor. Everything has its own duty and a reason to be born. 8)
The earth's magnetic field is ALWAYS changing day by day: I have found a nice document published by Istituto Nazionale di Geofisica (ING) the title is "Atti del 1° Convegno di geomagnetismo" authors A.Meloni and F.Molina in wich thre were 2 nice drawings forecoming from Regia Marina historical archives: an italian map from Supermarina, 1941 and a map of year 1900 received from Imperial Japanese Fleet. This is the proof that all Axis Navies were perfectly aware about the risks related to the management of any magnetic equipment in the waters close to Greenland and Iceland

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Post by Serg12 » 12 Aug 2005 13:51

>5. The torpedoes, if they missed the target, often blew themselves up when they reached the end of their run

Interestingly why? If they have only magnetic fuse the explosion at hit in a sea bottom is excluded. And they can not blow up themselves if it is not stipulated by specification..

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Post by gabriel pagliarani » 12 Aug 2005 15:27

Serg12 wrote:>5. The torpedoes, if they missed the target, often blew themselves up when they reached the end of their run

Interestingly why? If they have only magnetic fuse the explosion at hit in a sea bottom is excluded. And they can not blow up themselves if it is not stipulated by specification..
This is a solely your own deduction: those U-boots never went back to report about their sinking. No known navy in the world launched torpedoes armed with only a fuze: there must be ALWAYS a time-fuze for arming and extra-course and it could be excluded only by direct explicit order of the Captain. No double YES, no detonation possible in close proximity of the launcher, but human errors or madness are always possible.

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Uninen
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Post by Uninen » 13 Aug 2005 19:18

tommy303, thanks for sharing the more detailed info. And now as i remember, i did learn about the method on some documentary what was mainly about German magnetic mines and how their treath was countered.. well part of it was anyways.

Thanks.

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Post by Trommelfeuer » 13 Aug 2005 21:38

Gentlemen, you should also read The Norwegian Operation and the Torpedo Crisis on uboat.net.
The article is well worth reading it, it describes the problems, gives interesting examples of failed torpedo attacks and good background info...
The problems with magnetic pistols in the various torpedos, British, German and American, had mainly to do with lack of understanding about the earth's magnetic fields--ie there were areas where magnetic anomalies tended to fox the pistols, triggering them as soon as the torpedo finished its arming run.
There was also this problem:
...On January 30, the crew of U-94 made a little extra effort and conducted an on-board examination of their torpedoes amidst the Atlantic. They thus discovered an excess pressure in the torpedoes' balance chambers, where the hydrostatic valve controlling the depth at which the 'fish' ran was located. When they radioed back their findings, the Inspector of the Torpedo Department ordered a check on board all submarines in port. Half of the torpedoes were found to have the same problem, and the mystery of the torpedoes' deeper-than-set-depth run was finally fathomed. The results of this and later investigations were summed up into a Memorandum by Grand Admiral Raeder on Feb 9, 1942.

But what was this higher pressure in the chambers due to? According to Dönitz's memoirs, the higher than normative pressure (the normative was atmospheric) in the chambers was due to the "frequent releases of compressed air which are essential when [the boat] [is] proceeding submerged" (92). During long periods of submersion, a considerable excess pressure thus accumulated. One can't help asking, hadn't the constructors foreseen such a problem? They had, indeed. Normally, no excess pressure should have accrued. However, many balance chambers were found not to be airtight - they had leaks. This discovery, added to magnetic influence from the Norwegian fjords, largely explained the stupendous failure of the boats during Operation Hartmuth, for many of them had remained submerged for as long as 20 hours daily. After the final computations were made, it was found that between 30 and 35 % of the torpedo attacks during the Norwegian campaign had been failures...
...Yea, you guesses it, quoted from the article mentioned above... :wink:

BTW, isn't this a nice photo... (source: Naval Historical Center )
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