Torpedo History

[Rolfo]

Torpedo History

The Torpedoes of WWII Documentary - YouTube
-   www.youtube.com/watch?v=AJttDDx0Axs&t=236s
-   https://youtu.be/AJttDDx0Axs

Das Video zeigt die Entwicklungs Probleme des Mark 14 Torpedos aus amerikanischer Sicht.
(Text und Sound leider nur in Englisch )

Ein sehr ausfuerlicher Teil des Videos beschaeftigt sicht mit diesen Problemen:
•   Magnetischer Zuender Mechanik
•   Aufschlag Zuender Mechanik
•   Tiefenruder Mechanik
•   Magnetische geographische Unterschiede fuer den Kreisel Kompass.

Dieselben Probleme mit denen auch die deutsche, englische und franzoesische Torpedo Entwicklung beschaeftigt war.


Video Reference:
•   Dieses Video wurde mir durch einen Fletcher Oldies Kameraden, Ernst Wendler zugestellt.
•   Das erste mal sah ich dieses Video waehrend meiner Ausbildung an dem Mark 15 Torpedo, Nachfolger des Mark 14, in der Torpedo Schule in Newport (1959).

Torpedo Krise Referenz:
•   Marinearchiv 2005 Re: "Die Torpedo-Krise 1939/40" -  12 Mai 2005.

Nicht nur die rein technische Probleme sondern auch die wirtschaftlichen Gruende und die mangelhafte Kommunikation zwischen den Dienststellen TVA und TEK, bei der Kriegsmarine und dem BuOrd (Bureau of Ordnance) und den Front Berichten der US Navy Commanders bei der US Navy waren die Haupt-Ursache, dass es bei dem Mark 14 der US Navy und dem G7 der Kriegsmarine zu einer Torpedo Krise fuehrte.
 
Teil 1 - Kriegsmarine

G7 Torpedo
Der G 7 hat ein Kaliber von 21 Zoll (entspricht 533 mm → Buchstabe ,,G") etwas über 7 Meter lang und wurde hauptsächlich in den beiden Ausführungen G 7a mit Dampfgasmotor (Brotherhood-Maschine) und G 7e mit Elektroantrieb (Gleichstrommotor) gebaut.
Der G 7e wurde auf U-Booten und der G 7a auf Überwassereinheiten und als Reservetorpedo auf U-Booten verwendet. Zu Beginn des Zweiten Weltkrieges kam es beim Einsatz durch U-Boote aufgrund ungenügender Erprobung von Serientorpedos, zu gehäuften Versagern der Torpedos vor allem in Kombination mit Magnetzündern. Dies wurde als Torpedokrise bezeichnet und führte dazu, dass die modernen Magnetzünder vorübergehend nicht mehr eingesetzt werden konnten.







Entwicklung
Die Entwicklung von Torpedos geschah in Deutschland zunächst durch die Firma Schwartzkopff während die Kaiserliche Marine ihre Torpedos anfangs von der Firma Whitehead in Fiume bezog. Jedoch schon Ende der 1870er Jahre wurde seitens der Marine in Eckernförde die sogenannte ,,Torpedowerkstatt" (heute: Wehrtechnische Dienststelle 71) zur eigenständigen Entwicklung und zum Einschießen der Torpedos eingerichtet. Diese entwickelte sich im Laufe der 1880er Jahre zunehmend zum Zentrum der Forschung und Produktion deutscher Torpedowaffen. Der verbliebene Teil der Torpedowerkstatt wurde nach dem Ersten Weltkrieg als Torpedoversuchsanstalt Eckernförde (TVA) fortgeführt. 1942 kam zusätzlich die Torpedoversuchsanstalt Neubrandenburg am Tollensesee hinzu. Beide TVA wurden 1945 gesprengt.

Torpedokrise  (Die amerikansiche Navy hatte genau dieselbe Probleme)
Im Jahr 1940 kam es in der deutschen Kriegsmarine zur sogenannten Torpedokrise, als vor allem während der Invasionsoperationen in Norwegen (Unternehmen Weserübung) viele U-Bootangriffe auf Schiffe misslangen, weil die G7-Torpedos versagten.
Die erst nach längeren Untersuchungen aufgefundenen und später abgestellten Fehler in den Torpedos waren hauptsächlich auf unzureichende Erprobungen, widersprechende Wirtschaftsinteressen sowie auf die Konkurrenz zwischen Torpedoerprobungskommando (TEK) und Torpedoversuchsanstalt (TVA) zurückzuführen.

Hintergrund
Der wichtigste Torpedo der deutschen Kriegsmarine war der seit 1934 serienmäßig hergestellte Typ G7. Diesen gab es als dampfgasbetriebene und elektrisch angetriebene Version, die entweder mit Aufschlagzünder oder einem neu entwickelten Magnetzünder versehen war. Die Variante mit Magnetzündung war wirkungsvoller, da diese unter dem Rumpf eines gegnerischen Schiffes explodierte und die dabei entstehende Gasblase den Kiel des Schiffes brach, wodurch dieses meistens unrettbar verloren war.
Schon kurz nach Ausbruch des Zweiten Weltkrieges häuften sich die Meldungen deutscher U-Bootkommandanten über Versager bei Torpedoschüssen. Die Torpedos liefen entweder unter den gegnerischen Schiffen einfach hindurch oder explodierten weit vor oder nach dem Ziel oder aber gar nicht. Zwei frühe Vorfälle sind dabei besonders erwähnenswert: Zwölf Tage nach Kriegsausbruch schoss U 39 zwei Torpedos aus einer Entfernung von nur 800 m auf den britischen Flugzeugträger Ark Royal, die aber vorzeitig detonierten; und Ende Oktober konnte sich U 56 einem Flottenverband mit den damals größten Schlachtschiffen der Royal Navy (Hood, Nelson und Rodney) nähern und einen Dreier-Fächer auf die Nelson schießen, wobei die Torpedos auf den Rumpf aufschlugen, aber nicht explodierten.
Der Höhepunkt der Krise wurde im Frühjahr 1940 erreicht, als während der Invasion in Norwegen eine Vielzahl von abgeschossenen Torpedos versagte. Nachträglich kam man zu der Schätzung, dass bei funktionierenden Torpedos mindestens Treffer auf einem Schlachtschiff, sieben Kreuzern, sieben Zerstörern und mehreren Transportschiffen erzielt worden wären.[2] Trotz Massierung gegnerischer Schiffe und guter Schusspositionen konnten in norwegischen Gewässern jedoch mit einer Ausnahme keine wirksamen Torpedotreffer erzielt werden.

Reaktionen
Für die Besatzungen der U-Boote war die Torpedokrise eine deprimierende Erfahrung, die neben den technischen Fähigkeiten die Kampfmoral erheblich schwächte. Mehrmals waren Angriffe auf überlegene Kriegsschiffe trotz hervorragender Schusspositionen und umsichtigen Vorgehens gescheitert. Dadurch sahen sich zunächst die Befürworter einer deutschen Überwasser-Strategie mit Großkampfschiffen bestätigt. Admiral Dönitz verwies jedoch auf die potentiellen Möglichkeiten, die sich der U-Boot-Waffe bei funktionierender Torpedotechnik böten.
Noch im Laufe des Norwegenfeldzugs wurde von Dönitz darum die Weisung gegeben, nur noch Torpedos mit Aufschlagzünder zu benutzen. Die Torpedos wurden mit einem Umschaltmechanismus versehen, so dass nun manuell von Magnetzündung auf Aufschlagzündung gewechselt werden konnte. Allerdings kam es auch mit Aufschlagzündern bei Schüssen durch U-Boote vermehrt zu Versagern.

Ursachen
Für das Versagen der Torpedos waren hauptsächlich zwei Bauteile verantwortlich: die Tiefensteuerung und die Gefechtspistole mit der Zündeinrichtung. Bei den regelmäßig zu tief und damit unter den Zielen hindurch laufenden Torpedos stellte sich heraus, dass die maximale Abweichung der voreingestellten Tiefe nicht wie vorgesehen einen halben Meter, sondern bis zu drei Meter betrug. Dies wurde durch einen zu hohen Luftdruck im Inneren der Torpedos verursacht. Dadurch steuerte das Ventil, das aus der Differenz zwischen Innendruck des Torpedos und dem umgebenden Wasserdruck die Tiefe feststellte, den Torpedo tiefer als beabsichtigt. Der hohe Druck in den Lagekontrollkammern der Torpedos entstand, da diese nicht luftdicht waren und der Druck im Torpedoinnern anstieg, wenn das U-Boot während seiner Tauchfahrten Druckluft ins Bootsinnere ausstieß. Dass die U-Boote durch die britischen Abwehrstreitkräfte häufig und lange unter Wasser gedrückt wurden, verschärfte dieses Problem zusätzlich.
Die Fehler bei der Tiefensteuerung konnten allerdings nicht die Fehlzündungen erklären. Hier lag die Ursache beim Zündmechanismus, dessen empfindliches Relais sich wegen der Antriebsvibrationen bewegte und dabei den Zündkontakt auslöste. Als erschwerende Ursache kam hinzu, dass die natürlichen Schwankungen und Unregelmäßigkeiten des Erdmagnetfeldes in den nördlichen Breiten ebenfalls Auswirkungen auf die Magnetzünder hatten.
Die Aufschlagzünder konnten durch zu geringe Vorschnelllose des Schlagbolzens ein Verpuffen der Initialladung bewirken sowie bei Auftreffwinkeln unter 50° durch Verklemmung versagen.
Von einer Literaturquelle wird dagegen angenommen, dass eine Entmagnetisierung der vor Norwegen eingesetzten gegnerischen Schiffe und die Nichtberücksichtigung der in den norwegischen Fjorden besonders starken und schnell wechselnden Strömungen bei der Schießausbildung der U-Boot-Kommandanten eine wesentliche Rolle gespielt hat.

Gerichtsverfahren
1941 wurde von Dönitz das Reichskriegsgericht eingeschaltet, um die verantwortlichen technischen Offiziere und Beamten zur Rechenschaft zu ziehen. Aufgrund einer gewissenhaften Vorbereitung und Vielzahl technischer Fragen vergingen fast sieben Monate zwischen der Anklage im Mai und der Verurteilung im Dezember 1941. Das Gericht stellte fest, dass die Torpedos nicht den notwendigen Erprobungen unterworfen wurden, eine mangelhafte Kommunikation zwischen den Dienststellen TVA und TEK, aber auch zur Industrie herrschte und es eine zu hohe Zahl von Änderungswünschen einer bereits eingeführten Waffe gab. Der Leiter der TVA und der Inspekteur der Torpedo-Inspektion (vorgesetzte Dienststelle der TEK) sowie zwei technische Beamte der TVA wurden zu Haftstrafen verurteilt, kamen aber nach sechs Monaten wieder frei und waren danach wieder im Rüstungsbereich tätig. Im Prozess wurde weiterhin als grundlegende Schwachstelle aufgezeigt, dass es falsch war, die Entwicklung, Fertigungsvorbereitung und Erprobung einer behördlichen Einrichtung zu überlassen, woraufhin die Marine eine Aufteilung zwischen staatlichen Dienststellen und der Industrie forcierte.

Lösungen - Deutsche Torpedowerkstatt, Mai 1942
Schon im Herbst 1939 wurde unter dem Vorsitz des einstigen Chefkonstrukteurs des Torpedos Ernst-August Cornelius eine Arbeitsgemeinschaft gegründet, die die Probleme relativ schnell beseitigen konnte. Durch eine Vielzahl von kleinen Änderungen wurde die Tiefensteuerung verbessert und das Problem des empfindlichen Relais der Gefechtspistole durch eine verbesserte Aufhängung behoben. Ab Sommer 1940 galt der G7-Torpedo als kriegsbrauchbar und wurde ab 1941 wieder vollständig eingesetzt.
Im weiteren Verlauf des Krieges wurden dann von deutscher Seite Torpedos entwickelt, die druckunabhängig nach Programm oder Horchpeilung liefen, wie beispielsweise der Zaunkönig, FAT oder LUT.
Die US-amerikanische Marine hatte im Zweiten Weltkrieg vergleichbare Probleme, die unter dem Begriff Torpedoskandal bekannt wurden.
Das anfangs genannte Video "The Torpedoes of WWII Documentary – YouTube" zeigt in Wort und Bild die Geschichte der amerikanischen Torpedo Entwicklung und erklaert in grossem Detail die technischen und organisatorischen Kompetenz Probleme des Mark 14 Torpedos.



 
Teil 2- Mark 14 Torpedo

The Mark 14 torpedo had four major flaws.
•   It tended to run about 10 feet (3.0 m) deeper than set.
•   The magnetic exploder often caused premature firing.
•   The contact exploder often failed to fire the warhead.
•   It tended to run "circular", failing to straighten its run once set on its prescribed gyro-angle setting, and instead, to run in a large circle, thus returning to strike the firing ship.









Controversy
The Mark 14 was central to the torpedo scandal of the U.S. Pacific Fleet Submarine Force during World War II.
Inadequate production planning led to severe shortages of the weapon. The frugal, Depression-era, peacetime testing of both the torpedo and its exploder was woefully inadequate and had not uncovered many serious design problems. Torpedoes were so expensive that the Navy was unwilling to perform tests that would destroy a torpedo. Furthermore, the design defects tended to mask each other. Much of the blame commonly attached to the Mark 14 correctly belongs to the Mark 6 exploder. These defects, in the course of fully twenty months of war, were exposed, as torpedo after torpedo either missed by running directly under the target, prematurely exploded, or struck targets with textbook right angle hits (sometimes with an audible clang) and failed to explode.

Responsibility lies with the BuOrd, which specified an unrealistically rigid magnetic exploder sensitivity setting and oversaw the feeble testing program. Its pitiful budget did not permit live fire tests against real targets; instead, any torpedo that ran under the target was presumed to be a hit due to the magnetic influence exploder, which was never actually tested. Therefore, additional responsibility must also be assigned to the United States Congress, which cut critical funding to the Navy during the interwar years, and to NTS, which inadequately performed the very few tests made. BuOrd failed to assign a second naval facility for testing, and failed to give Newport adequate direction.
Some of these flaws had the unfortunate property of masking or explaining other flaws. Skippers would fire torpedoes and expect the magnetic influence exploder to sink the target ship. When the torpedoes did not explode, they started to believe the magnetic influence exploder did not work. Against orders, some submariners disabled the magnetic influence feature of the Mark 6 exploder, suspecting it was faulty, and went for contact exploder hits; such efforts would confuse the issues. Looking back in 1953, the BuOrd speculated, "Many shots planned for impact against the side of a ship missed because of deep running, yet damaged the enemy due to the magnetic influence feature of the Mark 6."
When later tests discovered the torpedoes ran deeper than set, the submarine command then believed that the torpedoes ran so deeply that the magnetic influence exploder could not sense the target ship; the failure to explode had been due entirely to the depth setting and that nothing was wrong with the magnetic influence exploder. When the depth issue was fixed, the magnetic influence exploder's premature detonation made it seem like the exploder was working but little damage would be done to the target ship. It was only after the magnetic influence feature was deactivated that problems with the contact exploder would be discernable.


Running too deep
On 24 December 1941, during a war patrol, Commander Tyrell D. Jacobs in Sargo fired eight torpedoes at two different ships with no results. When two additional merchantmen came in view, Jacobs took extra care to set up his torpedo shots. He pursued the targets for fifty-seven minutes and made certain the TDC bearings matched perfectly before firing two torpedoes at each ship from an average range of 1,000 yd (910 m). The shots should have hit, but all failed to explode.
A few days after he discovered the torpedoes were running too deep, and corrected the problem, Jacobs detected a big, slow tanker. Again, his approach was meticulous, firing one torpedo at a close range of 1,200 yd (1,100 m). It missed. Exasperated, Jacobs broke radio silence to question the Mark 14's reliability.
A similar experience happened to Pete Ferrall in Seadragon, who fired eight torpedoes for only one hit and began to suspect the Mark 14 was faulty.
Deep running torpedoes had been seen before. In January 1942, BuOrd told the fleet that the Mark 10 torpedo ran 4 feet (1.2 m) deeper than set. The reasons for deeper running are not explained, but the Mark 10 torpedo's speed had been increased from 30 to 36 knots, its warhead had been increased from 400 pounds to 497 pounds of TNT, and its guidance package had been updated.

Lockwood's depth tests
Shortly after replacing John E. Wilkes as Commander of Southwest Pacific submarines in Fremantle, Western Australia, newly minted Rear Admiral Charles A. Lockwood ordered a historic net test at Frenchman Bay on 20 June 1942. Eight hundred torpedoes had already been fired in combat, more than a year's production from NTS.
Jim Coe's Skipjack did the honors, firing a single fish with an exercise head, set at 10 ft (3.0 m), from 850 yards (780 m). It hit the net at a depth of 25 ft (7.6 m). Not satisfied, James Fife, Jr. (formerly Chief of Staff to COMSUBAS Wilkes, whom Lockwood was replacing) followed up the next day with two more test shots; Fife concluded they ran an average 11 ft (3.4 m) deeper than the depth at which they were set. BuOrd was not amused.
Neither was the CNO, Admiral Ernest J. King, who "lit a blowtorch under the Bureau of Ordnance". The fact that destroyers' Mark 15s were suffering the same failures may have had something to do with it as well. On 1 August 1942, BuOrd finally conceded the Mark 14 ran deep, and six weeks later, "that its depth-control mechanism had been 'improperly designed and tested'".

Depth explanation
The Mark 14 torpedo tended to run some 10 feet (3.0 m) too deep for several reasons. The first was that it was tested with an exercise warhead that was more buoyant than the warhead; that was a precaution made to avoid losing an expensive torpedo. The live warhead contained more mass, and it reached buoyancy equilibrium at a lower depth. Also, the depth mechanism was designed prior to the warhead's explosive charge being increased, making the torpedo even heavier overall. "Testing conditions became more and more unrealistic, obscuring the effect of the heavier warhead on depth performance." Furthermore, the depth testing device used by NTS to verify the torpedo's running depth (the depth and roll recorder) had the same measuring port placement error as the Mark 14's depth control port, so both were off by the same amount in the same direction and gave the impression that the torpedo was running at the desired depth when it was actually much deeper. After hearing of the deep-running torpedo problem, most submarine skippers simply set their torpedoes' running depth to zero, which risked broaching the torpedo.
Torpedo depth is a control problem; good depth control requires more than just measuring the torpedo's depth. A depth control system that used just depth (measured by a hydrostat) to control the elevators would tend to oscillate around the desired depth. Whitehead in Fiume supplied many of the world's navies, and it had trouble with depth control until it developed the "balance chamber" with pendulum (pendulum-and-hydrostat control). The balance chamber had water pressure push against a disk that was balanced by a spring. "The inclusion of a pendulum stabilized the mechanism's feedback loop." This development (known as "The Secret") was around 1868.
Depth control in early torpedoes such as the Mark 10 had been done with a pendulum mechanism that limited the torpedo to shallow pitches of less than 1 degree. The shallow angle meant that it could take a long time for a torpedo to stabilize at its desired depth. For example, to change depth by 30 feet (9.1 m) on a 1° slope takes a horizontal run of about 1,800 feet (550 m). The improved Uhlan mechanism (Uhlan gear) for depth control had much faster depth stabilization and had been introduced in the Mark 11 torpedo.
When the Uhlan gear was incorporated in the Mark 14 design, the pressure sensing port for the depth mechanism was moved from its position on the cylindrical body to the cone-shaped tail section; the designers did not realize that move would affect the pressure readings. The repositioning meant a hydrodynamic flow effect when the torpedo was moving created a substantially lower pressure at the port than hydrostatic depth pressure. The torpedo's depth control engine therefore thought the torpedo was too shallow depth and responded by trimming the torpedo to run deeper. A laboratory test (such as immersing a non-moving torpedo in a pool of water) would not be subject to the flow-induced pressure change and would show the torpedo trimmed at the desired depth. Dynamic tests using exercise heads with depth and roll recorders would have shown the depth problem, but the depth measuring port suffered from the same placement problem and gave consistent (though incorrect) measurements. The problem was also exacerbated by higher speeds. The depth problem was finally addressed in the last half of 1943 by relocating the sensor point to the midbody of the torpedo where hydrodynamic effects were minimized.

Magnetic influence exploder and premature explosions
Mark 6 Mod 1 exploder used early in the war. Later on it was replaced with the Mark 6 Mod 5.
By August 1942, the faulty running depth situation was resolved, and submarines were getting more hits with the Mark 14. However, curing the deep-running problem caused more premature and duds even as more hits were being achieved. The number of sinking's did not rise.
The deep running torpedoes would explain many warshot misses: a torpedo running too deeply under the target would not allow the magnetic influence exploder to detect the target. Getting the torpedoes to run at the correct depth would presumably fix the problem of the torpedoes failing to explode. This explanation satisfied Lockwood and Robert H. English (then COMSUBPAC), who both refused to believe the exploder could also be defective. In August 1942, the submarine command believed mistakenly that the torpedo reliability problem was solved.
The skippers, however, continued to report problems with the Mark 14. Suspicion about the magnetic influence exploder grew.
On 9 April 1943, USS Tunny attacked an aircraft carrier formation. ULTRA intercepts disclosed that all three torpedoes fired at the second carrier were premature explosions. The commanding officer stated, "The shallow [depth] setting thus caused the torpedo to reach the activating flux density of the exploder some fifty meters from the target."
On 10 April, USS Pompano attacked Japanese aircraft carrier Shokaku by firing six torpedoes. There were at least three premature explosions, and the aircraft carrier was not damaged.
On 10 April 1943, Bureau of Ordnance Chief Admiral Blandy wrote Lockwood that the Mark 14 was likely to explode prematurely at shallow depths. Blandy recommended that the magnetic influence feature be disabled if torpedoes were fired for contact hits.
BuOrd also concluded that the Mark 14's arming distance of 450 yards was too short; an arming distance of 700 yards would be needed for most torpedoes to stabilize their course and depth. BuOrd also believed the Mark 6 magnetic influence feature was less effective below 30°N latitude and did not recommend its use below 30°S latitude.
On May 8 1943, Lockwood made a list of torpedo failures gleaned from ULTRA intercepts.
On 10 June 1943, USS Trigger fired six torpedoes from 1200 yards at the aircraft carrier Hiyo. Two torpedoes missed, one exploded prematurely, one was a dud, and two hit. The carrier was damaged but made it home.
Uniquely, Lieutenant Commander John A. Scott in Tunny on 9 April 1943 found himself in an ideal position to attack aircraft carriers Hiyo, Junyo, and Taiyo. From only 880 yd (800 m), he fired all ten tubes, hearing all four stern shots and three of the bow's six explode. No enemy carrier was seen to diminish its speed, though Taiyo was slightly damaged in the attack. Much later, intelligence reported each of the seven explosions had been premature; the torpedoes had run true but the magnetic feature had fired them too early.
Many submarine commanders in the first two years of the war reported explosions of the warhead with little to no damage of the enemy. The magnetic exploders were triggering prematurely, before getting close enough to the vessel to destroy it. Earth's magnetic field near NTS, where the trials (limited as they were) were conducted, differed from the areas where the fighting was taking place.
Submarine skippers believed that about 10 percent of their torpedoes prematurely exploded; BuOrd statistics had the premature explosions at 2 percent.

Deactivation
At Pearl Harbor, despite nearly all his skippers' suspicions about the torpedoes, Rear Admiral Thomas Withers, Jr. refused to deactivate the torpedo's Mark 6 exploder, arguing torpedo shortages stemming from inadequate production at NTS made it impossible. As a result, his men did it on their own, doctoring their patrol reports and overstating the size of ships to justify using more torpedoes.
Only in May 1943, after the most famous skipper in the Sub Force, Dudley W. "Mush" Morton, turned in a dry patrol, did Admiral Charles A. Lockwood, Commander Submarine Force Pacific (COMSUBPAC), accept the Mark 6 should be deactivated, but waited to see if Bureau of Ordnance commander Admiral William "Spike" Blandy might yet find a fix for the problem. The Bureau of Ordnance sent an expert to Surabaja to investigate, who set the gyro backwards on one of Sargo's trial torpedoes; the potentially deadly setting, guaranteed to cause erratic running, was corrected by torpedo officer Doug Rhymes. Though he found nothing wrong with maintenance or procedures, the expert submitted a report laying all the blame on the crew.
In late June 1943, Rear Admiral Lockwood (by then COMSUBPAC) asked Commander-in-Chief of the Pacific Fleet (CINCPAC) Chester Nimitz for permission to deactivate the magnetic exploders. The next day, 24 June 1943, CINCPAC ordered all of his submarines to deactivate the magnetic exploder.

Rear Admiral Christie, who had been involved in the development of the magnetic influence exploder, was now commander of the Australian-based submarines in the South West Pacific Area and not in Nimitz' chain of command. Christie insisted his area's submarines continue to use the magnetic exploder. At the end of 1943, Admiral Thomas C. Kinkaid replaced Admiral Arthur S. Carpender as Commander Allied Naval Forces South West Pacific Area (Christie's boss) and ordered Christie to deactivate the magnetic influence exploder.

Premature explosion explanation
A torpedo may take a long time before it settles on its final course. If the torpedo direction is still changing when the torpedo arms, it may set off the magnetic influence exploder.
In 1939, before the war started for the U.S., BuOrd knew the magnetic influence exploder was suffering from unexplained premature detonations:
Evidence of that fact came in 1939, when Newport reported to the Bureau that the exploder was giving unexplained prematures. Admiral Furlong arranged for a physicist to visit the station and investigate the failures. For approximately a week, the scientist and his assistants worked with the device. Four sources of prematures were uncovered. Even more significant, the investigator reported to the Bureau that the responsible engineers at Newport were not employing proper tests on the Mark 6. Corrective steps were ordered by the Chief, but subsequent events proved that the remedial action, like the original tests, was inadequate.
There were two common types of premature explosions. In the first, the warhead exploded just as it armed. These premature explosions were easily discerned by the submarine because the torpedo exploded before it had a chance to reach its target. In the second, the warhead exploded just before reaching the target ship but far enough away that it did no damage. The skipper, looking through the periscope, could see the torpedo run right to the ship and see the explosion; the crew could hear the high order explosion. Everything would look OK except that the target ship would get away with little or no damage. Sometimes the submarine command would hear about these premature explosions from intercepted enemy communications.
Both premature explosion types could result from the magnetic influence exploder. If a torpedo was still turning to get on course or had not stabilized its depth when the warhead armed, the exploder could see a magnetic field change and detonate. As the warhead approached the target, it could sense a change due to the ship's effect on the earth's magnetic field. That's a desired effect if the torpedo is set to run under the ship, but not a desirable effect when the torpedo is set to hit the side of the ship.
Another explanation for early premature explosions was electrical failure due to leaking gaskets.
The second type of premature explosion masked contact exploder failures. Skippers firing the torpedo for a contact exploder hit on the side of the target would see an explosion and believe the contact exploder worked, but the explosions were triggered not by the contact feature, but rather by the magnetic influence feature at a distance far enough from the hull to cause little or no damage.

Contact exploder
Detail of Mark 6 exploder. For contact operation, the collision of the torpedo with the target ship would move the firing ring and release the firing pin stem. The firing pin stem would then move vertically (powered by the firing spring) and detonate the tetryl booster charge. The mechanism worked for low-speed torpedoes, but for the high-speed Mark 14 torpedo, the same impact deceleration that caused the firing ring to move was also large enough to cause the firing pin stem to bind and fail to detonate the booster.
Inactivation of the magnetic influence feature stopped all the premature explosions.
Early reports of torpedo action included some dud hits, heard as a dull clang. In a few instances, Mark 14s would strike a Japanese ship and lodge in its hull without exploding. The contact pistol appeared to be malfunctioning, though the conclusion was anything but clear until running depth and magnetic exploder problems were solved. The experience of Dan Daspit (in Tinosa) was exactly the sort of live-fire trial BuOrd had been prevented from doing in peacetime. It was now clear to all at Pearl Harbor the contact pistol was also defective. Ironically, a direct hit on the target at a 90 degree angle, as recommended in training, would usually fail to detonate; the contact pistol functioned reliably only when the torpedo impacted the target at an oblique angle.
Once the magnetic influence exploder was deactivated, problems with the contact exploder became more apparent. Torpedoes would hit their target without detonating. There might be a small "explosion" when the air flask ruptured due to the impact with the target.
Daspit carefully documented his efforts to sink 19,000-ton whale factory ship Tonan Maru III on 24 July 1943. He fired four torpedoes from 4,000 yd (3,700 m); two hit, stopping the target dead in the water. Daspit immediately fired another two; these hit as well. With no enemy anti-submarine combatants in sight, Daspit then took time to carefully maneuver into a textbook firing position, 875 yd (800 m) square off the target's beam, where he fired nine more Mark 14s and observed all with his periscope (despite the Japanese firing at it). All were duds. Daspit, suspicious by now he was working with a faulty production run of Mark 14s, saved his last remaining torpedo to be analyzed by experts back at base. Nothing out of the ordinary was found.

Lockwood's drop tests
Daspit's cruise raised enough of an issue that tests were carried out by COMSUBPAC's gunnery and torpedo officer, Art Taylor. Taylor, "Swede" Momsen, and others fired warshots into the cliffs of Kahoolawe, beginning 31 August. Additional trials, supervised by Taylor, used a crane to drop warheads filled with sand instead of high explosive from a height of 90 feet (27 m) (the height was chosen so the terminal velocity would match the torpedo's running speed of 46 knots). In these drop tests, 70% of the exploders failed to detonate when they hit the target at 90 degrees. A quick fix was to encourage "glancing" shots (which cut the number of duds in half), until a permanent solution could be found.

Contact exploder explanation
The Mark 6's contact exploder mechanism descended from the Mark 3 contact exploder. Both exploders had the unusual feature that the firing pin's travel was perpendicular to the torpedo's travel, so the firing pin would be subject to side loading when the torpedo struck its target. The Mark 3 exploder was designed when torpedo speeds were much slower (the Mark 10 torpedo's speed was 30 knots), but even then the Mark 3 prototypes had problems with the firing pin binding during the high deceleration when the torpedo collided with the target. The solution was to use a strong firing spring to overcome the binding.The Mark 14 torpedo had a much higher speed (46 knots), so it would see significantly higher deceleration, but BuOrd apparently just assumed the contact exploder would work at the higher speed. There were no live-fire tests of the Mark 14 torpedo, so there were no-live fire tests of its contact exploder. If BuOrd had tried some live-fire tests of the contact exploder during peacetime, it probably would have experienced some duds and rediscovered the binding problem.
Pearl Harbor made working exploders by using lighter weight aluminum parts. Reducing the mass reduces the binding friction. BuOrd suggested using a stiffer spring, the fix that had worked decades before. In the end, BuOrd adopted a ball switch and electric detonator rather than using a firing pin mechanism.
In September 1943, the first torpedoes with new contact pistols were sent to war. "After twenty-one months of war, the three major defects of the Mark 14 torpedo had at last been isolated. Each defect had been discovered and fixed in the field—always over the stubborn opposition of the Bureau of Ordnance."

Circular runs
There were numerous reports of the Mark 14 running erratically and circling back on the firing boat. A circular run sank the submarine Tullibee, but it may not have been a Mark 14. Likewise, Sargo was almost sunk by a circular, but the circular run happened because the gyro had not been installed. The subsequent Mark 18 torpedo was no better, sinking Tang. The Mark 15 torpedo had collars to prevent circular runs, but the Mark 14 was never given this feature.

Resolution
Once remedied, sinkings of enemy ships rose noticeably. By the end of World War II the Mark 14 torpedo had become a much more reliable weapon. Lessons learned allowed surface ships such as destroyers to remedy the failings of the Mark 15; the two designs shared the same strengths and faults.
After the war, the best features of the improved Mark 14 were merged with the best features of captured German torpedoes to create the hydrogen peroxide–fueled Mark 16 with a pattern-running option. The Mark 16 became the standard United States post-war anti-shipping torpedo, despite the large remaining inventory of Mark 14 torpedoes.

[didi1]

Moin Rolfo,

Danke Rolfo das war mal wieder ein interessanter Beitrag.

Gruß
Ditmar

[bettika61]

Hallo Rolfo,
danke für Deinen Beitrag

Jedoch schon Ende der 1870er Jahre wurde seitens der Marine in Eckernförde die sogenannte ,,Torpedowerkstatt" (heute: Wehrtechnische Dienststelle 71) zur eigenständigen Entwicklung und zum Einschießen der Torpedos eingerichtet.

Die Torpedowerkstatt wurde 1877 in Kiel-Friedrichsort eingerichtet, die ab 1891 den Namen "Kaiserliche Torpedowerkstatt" führte.
Der Schießstand in Eckernförde (heute WTD 71 Eckernförde Süd) wurde erst 1913 errichtet.

1942 kam zusätzlich die Torpedoversuchsanstalt Neubrandenburg am Tollensesee hinzu. Beide TVA wurden 1945 gesprengt.

Es gab noch mehr TVA . 1934 wurde die TVA Eckernförde Nord (heute Marinestützpunkt Eckernförde und WTD 71 Nord) gebaut, es folgte 1938 die  TVA Ost in Surendorf. Es gab auch noch die TVA in Gotenhafen .

P.S In welchem Museum wurde das Foto des Torpedo aufgenommen?

[Rolfo]

Ditmar, Beatte,
danke fuer die Beurteilung. Die wirklich interessante Informationen sind leider nur im Video (in englischer Sprache) zu finden.

Bill Hagedorn ein US Navy Torpedo Mate hat mir 1959 in der Newport Torpedo Schule viele interessante Einzelheiten aus seiner Erfahrung mitgeteilt.

Beatte: Das Photo von dem G7 habe ich im Canadian Ottawa War museum gefunden.

Greetings from a Tin Can Sailor

[jost_brune]

Das Ermittlungsverfahren wurde von Großadmiral Erich Raeder angeordnet, nicht von Dönitz - Dienstvorgesetzter.

... der Inspekteur der Torpedo-Inspektion (vorgesetzte Dienststelle der TEK) ... verurteilt

Vizeadmiral Friedrich Götting, Inspekteur der TI wurde freigesprochen.

[Schorsch]

Hallo Rolfo,

ich hätte bezüglich der hervorgehobenen Behauptung eine Nachfrage:

(...)
G7 Torpedo
Der G 7 hat ein Kaliber von 21 Zoll (entspricht 533 mm → Buchstabe ,,G") etwas über 7 Meter lang und wurde hauptsächlich in den beiden Ausführungen G 7a mit Dampfgasmotor (Brotherhood-Maschine) und G 7e mit Elektroantrieb (Gleichstrommotor) gebaut.
(...)

In der Zeit zwischen den Weltkriegen gab es deutsche Torpedos mit dem Kennbuchstaben G. Allerdings hatten die aber kein Kaliber von 21'. So zum Beispiel die Torpedos vom Typ G/7s aus dem Jahr 1926, die G/7v, ebenfalls von 1926 und die vom Typ G/7v* von 1928 mit jeweils 500 mm. Solche Torpedos gehörten bis ca. 1934 zur Bewaffnung des Panzerschiffes DEUTSCHLAND und der leichten Kreuzer EMDEN, KÖNIGSBERG, KARLSRUHE, KÖLN und LEIPZIG. Auch die Torpedoboote der Raubvogel- und Raubtierklasse führten solche 500 mm-Torpedos.
Noch seltsamer wird das Ganze, wenn man die Zeit um 1916/17 mit in die Betrachtung einbezieht. Die von Whitehead in St. Pölten für die deutsche Marine gebauten G/250-Torpedos hatten Durchmesser von 450 mm. Insoweit scheint mir die Gleichsetzung G = 533,4 mm nicht gesichert.

Seltsam ist auch Deine Herkunftsbezeichnung Ottawa für die Fotos des G7a. Die Google-Bildersuche verortet z.B. Dein erstes Bild z.B. nach Oslo. Guckst Du hier: Klick! Für das zweite Bild habe ich als Aufnahmeort das Museumsuboot U-WILHELM BAUER in Bremerhaven gefunden. Auch hier ein entsprechendes Klick!

Mit freundlichen Grüßen
Schorsch

[Rolfo]

Hello Schorsch,
please forgive my response to you in English, but I want to make sure that I am not misunderstood.

I appreciate your "combing" (editing) of my torpedo history contribution for accuracy.
However, I feel you missed the essence of my Torpedo history, which was referring to the mishandling and miscommunication between different entities in the German as well as the US Navy that led to the Torpedokrise in the 40ties, for both navies, when you so nicely refer to my "hervorgehobene"  Behauptung:

Der G 7 hat ein Kaliber von 21 Zoll (entspricht 533 mm → Buchstabe ,,G") etwas über 7 Meter lang, when there were G7 Torpedos in 1926, 1928, and 1934 that  measured 500 mm.

As far as the photos are concerned you are right when you place my published photo in the Oslo instead the Ottawa museum. As it so happens G7 torpedo's of the WWII area are displayed in many museums. I goofed up.

I am always astonished when I see the many "Adleraugen" (geniuses, polymath's, gurus's and sage's) in the Marinearchiv that keep the contributors honest.

Join me in my motto:
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[Natter]

In der Zeit zwischen den Weltkriegen gab es deutsche Torpedos mit dem Kennbuchstaben G. Allerdings hatten die aber kein Kaliber von 21'. So zum Beispiel die Torpedos vom Typ G/7s aus dem Jahr 1926, die G/7v, ebenfalls von 1926 und die vom Typ G/7v* von 1928 mit jeweils 500 mm. Solche Torpedos gehörten bis ca. 1934 zur Bewaffnung des Panzerschiffes DEUTSCHLAND und der leichten Kreuzer EMDEN, KÖNIGSBERG, KARLSRUHE, KÖLN und LEIPZIG. Auch die Torpedoboote der Raubvogel- und Raubtierklasse führten solche 500 mm-Torpedos.
Noch seltsamer wird das Ganze, wenn man die Zeit um 1916/17 mit in die Betrachtung einbezieht. Die von Whitehead in St. Pölten für die deutsche Marine gebauten G/250-Torpedos hatten Durchmesser von 450 mm. Insoweit scheint mir die Gleichsetzung G = 533,4 mm nicht gesichert.

The "G" is a correct designation for Kriegsmarine 533,4 mm torpedoes. I don't know what designations were used before Kriegsmarine, so the use of the letter "G" in earlier german torpedeoes of 450 and 500 mm might be different.

I have posted an explanation of the Kriegsmarine (and Luftwaffe) torpedodesignations in this Wikipedia-article: https://en.wikipedia.org/wiki/List_of_World_War_II_torpedoes_of_Germany


For your conveniance, here is the text, describing the Kriegsmarine-designations:

The first letter indicates the diameter*:
    G = 53 cm (21")
    F = 45 cm (17.7")
    H = 60 cm (23.7")
    M = 75 cm (30")

The number indicates the length*:
    7 = 7 m
    6 = 6 m
    5 = 5 m

Next letter(s) indicates specific features regarding propulsion and control:
    a = Atem, i.e. Pressluft/Dampfgemisch-Antrieb (pressurized air/steam engine)
    e = elektrischer Antrieb (electric engine)
    f = Fernlenkung (remote control by radio or cable)
    d = Sauerstoff/Dampfgemisch-Antrieb (oxygen/steam engine)
    p = Primärbatterie-Antrieb (primary battery propulsion)
    m = Verbrennungsmaschine mit Kreislaufverfahren (combustion engine recirculating air)
    u = Sauerstoffträger Ingolin spurenfreier Antrieb (oxygen/steam engine with hydrogen peroxide as source for air, and no exposing "bubbletrack")
    x = Torpedo mit 3-Achsen Steuerung (3-axes control)
    r = Raketen- oder Düsenantrieb (rocket- or jet propulsion)
    s = Schall, Torpedo mit akustischen Suchkopf (acoustic seeker)
    t = Turbinenantrieb (turbine-engine)

"r" and "t" were only used with "u" to further denote the features of the ingolin-torpedoes. Some sources claim that "s" only was used with "a" to denote the development of G7a with acoustic seeker-capability; however, it was by no doubt used for the electric torpedoes with acoustic seekers (as "es" or just "s").

When the torpedo reached production status and was fielded (i.e. ready for operational usage), Kriegsmarine gave it a short designation "T", or "Torpedonummer", with the number given in Roman lettering (TI, TII, TIII, TIV etc.). For different versions of the main torpedo, a small Arabic letter was added (for example TIIId, TVa etc.) denoting specific/minor changes within the main design.

There were 7 different G7a torpedoes and 20 different G7e torpedoes, so the "Torpedonumber" is crucial to identify the exact type. The correct nomenclature for Kriegsmarine torpedoes are: "large letter" "number" "small letter" ("torpedonumber in paranthesis"), ie G7a(TI), G7e(TIII), G7ef(TX) etc.

* Note that diamteres and lenghts could vary between the different torpedoes, so this is just an approximate value (for example, the length of a G7a is 7163 mm)!

Seltsam ist auch Deine Herkunftsbezeichnung Ottawa für die Fotos des G7a. Die Google-Bildersuche verortet z.B. Dein erstes Bild z.B. nach Oslo.

It's located at the armed forces museum (Forsvarsmuseet) at Akershus Castle in Oslo.