View Full Version : SH4 - US Dud Torpedo's - Interesting - You Have Been Warned!

02-24-2007, 01:38 AM
The USN had a torpedo problem from the beginning of the war through mid-1943. For a year and a half, sailors put their lives on the line to make torpedo attacks with faulty equipment. If the duds had been able to effectively damage or destroy their targets, the Japanese expansion may have been more contained and the long path to ending the war may have been shorter and achieved earlier.

There were at least three problems with the Mark 14 submarine launched torpedo.
1. Running depth. (a.) Warheads were heavier than test heads. The wartime torpedo ran with a head down trim. The shore establishment eventually acknowledged a four foot error in running depths. Fleet tests in Australia found an 11 foot depth error. It was not until Aug'42 that a compromise of 10' was agreed and a trim repair kit was issued to the fleet later in that year.
Running depth. (b.) The depth sensor was designed for a slower running torpedo. The pressure gradient over the torpedo surface at higher speeds gave the wrong feedback. The sensor was later relocated to a neutral position.
2. The magnetic exploder was designed in the northern latitudes and did not work as well at the equator. The British and Germans had already disabled their magnetic exploders before the USN ordered theirs disabled 24June43. ComSubSWPac had participated in the development of the magnetic exploder, knew the principle was sound, and resisted disablement until Dec'43.
3. The conventional contact exploder was designed for the earlier, slower, 33 knot, Mk 13 torpedo. The newer, faster, 46 knot, Mk 14 torpedo had higher inertial impacts that would cause the firing pin to miss the exploder cap.

How could these problems have gone unknown?
1. Depression era economics found a torpedo to be expensive to the fleet budget. Therefore torpedoes were not tested to destruction; they were fired against soft targets with floatable warheads so they could be salvaged for reuse.
2. The magnetic exploder was kept secret and had a complicated technique of attachment to the installed contact exploder so that the magnet device did not have to be issued to the fleet until needed for wartime patrol. With minimum testing and fleet experience, the problems were unknown.
3. A single source of development, NTS Newport, meet reports of torpedo problems with disbelief that there could be anything wrong with what they considered were good designs that tested fine under controlled conditions. The problems first had to be proven by fleet units before the resources of the NTS were brought to bear.
4. Multiple problems take longer to find then does a single problem. Once a specific problem was uncovered, it could be quickly fixed. Only when the first problems was solved, could the nature of the succeeding problems be addressed, all in sequence.
Ref : Torpedo Scandal of 1942-1943; from the October 1996 issue of THE SUBMARINE REVIEW.

Related torpedoes.
Mark 10 . The older, slower, non-magnetic equipped torpedoes used in the older S-boats did not have these problems.

Mark 13 Air Launched Torpedo.
This 2,200 pound weapon had been introduced in 1938, had not been adequately tested, but was the only one available. Its use required release at less than 60 feet and slow speed. Over a year after the Battle of Midway and after some improvements, the Bureau of Ordinance ran a test with over 100 torpedoes and found only 31 percent gave a satisfactory run. Add to this -- exploder problems and erratic launches under fire against evading targets -- it is no wonder that dive bombing became the attack method of choice.
"Black Cat Raiders" by R. C. Knott
The Mk 13 aerial torpedo dated from the early 1930s. It was stubby. It's warhead originally carried 400 pounds of TNT, later 600 pounds of Torpex, that made it nose-heavy. Fleet squadrons limited drops to 50 feet at no more than 110 knots from a range of approximately 800 yards. Performance was so bad (until improved in 1944) as to make American torpedo-plane attacks well nigh futile.
"Unknown Battle of Midway" by Alvin Kernan
* Lea -- 13 launched, one hit ; in harbor
* Tulagi -- 22 launched, one hit ; in harbor
* Shoho -- 24 launched, 7 hits ; already damaged by bombs
* Shokaku -- 20 launched, no hits.
* Midway -- 51 torpedoes carried, no hits, 43 planes lost.
* Suzuya -- 6 torpedoes, improved Mod2, 3 reported explosions. Japs reported none.
Tactical Problem . The torpedo was so slow and short range that a ship could outrun a torpedo not launched from ahead. The TBD Devastator was too slow to get ahead of a turning ship. The torpedo made a clear wake allowing ships to steer away from its path. Some were observed in clear water on stationary targets to go under the enemy ship and detonate on the other side. Slow air speed allowed fighters to easily catch the torpedo bombers and approaches to 800 yards allowed hits by all calibers of anti-aircraft guns. The model 2, was introduced after Midway : many reported hits were actually premature explosions, according to Japanese records.
Further improvements in 1943 allowed drops at higher speeds and altitudes and resulted in 40% hit rates. Six engagements listed above with 136 torpedoes scored 7%, sinking transport Yokohama Maru, destroyer Kikuzuki, and light carrier Shoko.

Mark 15 . Destroyer Launched Torpedo
This had all the same mechanisms as the Mk 14. It was just slightly larger version and should have had all of the same problems. Deployment and analysis of hits, misses, and duds between the submarine and surface fleet differed. A measured attack by a submarine would cause immediate note of a failure and trigger analysis of the cause. A destroyer launched torpedo attack was in face of greater excitement; failures to hit while engaged in surface combat were not able to be immediately analyzed. After the battle, torpedo failures were simply attributed to misses. The poor performance of destroyer torpedo attacks can take on a new perspective, and need not be completely attributed to problems with tactics. Witness the failure to scuttle Hornet with nine torpedoes.

"It is sadly true that each modern torpedo type sent to war by the United States Navy was defective. ... The failure to test this crucial weapon prior to hostilities created the greatest technological failure in the history of American military." -- "Fire in the Sky" by Eric Bergerud.