Mark 14 Torpedo

Re posted in post # 2 per OP.

 

Some of us have watched the John Wayne movie, "Operation Pacific" which had a plot feature that their subs torpedoes did not explode properly or were otherwise ineffective.

At the start of WWII our subs were equipped with Mark 14 torpedoes, but history records little impact of our valiant submarine force in 1942 and until about September 1943.

One of Admiral Nimitz hallmark characteristics was his uncanny, some say genius skill in choosing commanders. Chester chose Charles A. Lockwood. Here is a snippet from the internet:

He (Lockwood) pushed the Navy's Bureau of Ships and Bureau of Ordnance to provide his men with the most effective submarines and torpedoes possible. He oversaw the tests that proved the unreliability of U.S. torpedoes, which at the time were often running too deep or failing to detonate, and prompted the improvements that made them the highly effective weapons they became in 1944 and 1945​

One of the surest ways any organization will fail is if the groups or people within the organization do not stick to the truth. What our subs inherited were faulty torpedoes that were inadequately tested by the makers. The Mark 14 had four separate problems which masked each other, making the solution difficult and comprised of partial fixes.

First the torpedo ran about 11 feet deeper than its setting, so it passed under some of its targets. Its water pressure sensor, hence its depth sensor was poorly located such that at speed (it could reach 46 knots) the high flow past the sensor produced a lower pressure than the actual static depth. This problem was found and the sensor relocated.

Second its magnetic trigger sometimes caused premature explosion when it armed a long way from the target, and sometimes exploded just before it reached the target when it first sensed the magnetic flux change produced by the target ship. One of the mistaken beliefs was that the torpedo hit the target because if observed the explosion occurred next to the target. Not observed was the explosion occurred just outside the effective range, so the explosion caused little or no damage. They could not understand why the Japanese torpedoes packing a little more than half the explosive power, did so much more damage. When the near target but premature explosion issue was discovered, the initial fix was to disable that trigger.

Third, the mechanical trigger, actuated by the torpedo impacting the target ship, often mechanically bound up such that the torpedo did not explode. Initially some improvement was achieved when the material was changed to a lighter metal. The lower mass results in a lower number of binding events and thus more proper explosions. Eventually the trigger was redesigned.

The fourth problem was with the guidance gyro. Sometimes a sub launched Mark 14 would circle and threaten or hit the firing sub. We lost two subs from the malfunction. The fix was simply to incorporate the design feature, restricting collars, that prevented that malfunction in the destroyer launched Mark 15's.

Thus by about September 1943, our "silent service" began to howl.

Epilogue - Admiral Lockwood is buried next to the graves of Admiral Nimitz and Admiral Spruance and Admiral Turner, near San Francisco