Torpedo scandal

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Like the Germans with the torpedo crisis , the Americans had persistent problems with torpedo failures throughout World War II . The US Navy torpedo scandal dragged on over a longer period between December 1941 and August 1943. However, the roots are even further back.

Both the depth control and the magnetic and impact fuze of the then current steam -gas powered submarine torpedo Mk 14 of the US Navy were affected. There were hardly any problems with the destroyer version Mk 15 . However, misses and failures in the fast destroyer battles could probably be less clearly differentiated than with the better controlled torpedo shots from the submarine. In any case, the torpedoes hardly differed technically.

The first problem with the Mk-14 torpedo was depth control, which had errors in at least four areas:

  1. Differences between calibration and combat shots: The torpedo weight and weight distribution changed when converting to a combat torpedo, as the warhead was heavier than the dummy head used for calibration. In addition, the conditions during the calibration shots were different than in battle. For calibration, surface ships were fired and not submerged torpedo tubes. In addition, the speeds at which the torpedo exited the tube, as well as the acceleration after launch, were different than under combat conditions.
  2. Design and manufacturing defects that changed calibration over time or environment, such as leaky envelopes.
  3. Incorrect calibration, such as failure to check against an absolute standard or excessive reliance on hydrostatic depth calculations without ever verifying the accuracy of the data obtained from it.
  4. Insufficient technical understanding. For example, the importance of water flow and pressure on the surface of a fast torpedo has been ignored. The combat torpedo ran about three meters lower than the calibration torpedo, which was due to the heavier warhead and the incorrect installation of the pressure sensor.

The second problem was the fluctuating sensitivity of the magneto in the Mk-6 ignition unit. The magneto ignition technology was not fully developed and tended to fail, and the development of the magnetic sensors did not take into account the different magnetic field strengths in different parts of the world. After individual submarines did not report a single ignited torpedo after deployments, Chester Nimitz , the then Commander in Chief Pacific, CinCPac for short, had all torpedoes with magneto detonators sorted out on June 24, 1943 and replaced by those with impact fuses.

After the depth control problems were resolved and the magneto was deactivated, the percussion fuse emerged as a third problem. At the beginning there were a number of duds , i.e. impacts on the target without an explosion. The force of impact required to trigger the Mk-6 detonator was exactly the same as that of the Mk-4 and Mk 5 detonators that were used in the older Mk-13 torpedo . However, at 33.5 knots , the Mk-13 torpedo was  significantly slower than the Mk-14 torpedo, which had a speed of 46.3 knots. The impact of the Mk 14 was almost twice as strong, so that when it was hit, the vertical plug connections to the detonator were bent so much that they missed the detonator. With oblique hits the forces were lower and the detonator worked more often. After recovering a failure after a test shoot on a reef , the problem was fixed.