World War II, Pacific, 1942           Flag
Dud Torpedoes                  

    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. The Asiatic Fleet submarines made 136 attacks, firing 300 torpedoes in the first four months sinking only ten ships. 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 cross-wise mounted 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. The effects were failure to explode or to explode prematurely.
  3. A single source of development, NTS Newport, met 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 problem was solved, could the nature of the succeeding problems be addressed, each in sequence.
       Ref : Torpedo Scandal of 1942-1943; from the October 1996 issue of THE SUBMARINE REVIEW.

    Related torpedoes.
    Mark 10 Submarine Torpedo. The older, slower, non-magnetic equipped torpedoes used in the older S-boats had one less of these problems. An error in its running depth was corrected by BuOrd just after Pearl Harbor ; it had run 4 feet too deep. It also had its share of prematures, erratic running, and other problems. Some subs and torpedoes were making hits, the problems were assumed to be human errors. Many good skippers were relieved for not sinking ships, when it was the torpedo's fault.

    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 air 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 design 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

      Air Attacks
    • 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 Mod 2, three reported explosions. Japanese reported no hits.

    Tactical Problem . The torpedo was so slow and short range that a warship could outrun one of our torpedoes when not launched from ahead. The TBD Devastator torpedo bomber 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 shoot them down and a required approach to 800 yards allowed hits from all calibers of ship-borne anti-aircraft guns. The model 2 was introduced after Midway : many reported hits were actually premature explosions, according to Japanese records. Therefore many reported hits and sinkings were false.
    Further improvements in 1943 allowed air drops at higher speeds and altitudes and resulted in 40% hit rates. The six engagements listed above with 136 torpedoes scored 7%, sinking only 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 (longer) 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 the face of greater excitement, usually at night ; 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 by the crew. 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 destroyer torpedoes.

    The torpedo station at Cavite Naval Station (Manila) destroyed on 10 Dec included 2/3 of Asiatic Fleet torpedoes. This created a shortage such that many targets that would have been attacked with four torpedoes were targeted with only two. Even so, more torpedoes were fired in the first year than reached the fleet-- production was fouled up, too. Some subs were reduced to carrying half loads of torpedoes and had to take mines instead.

    Torpedo tubes were not reliable. Of the nine torpedoes attempted by subs at Midway, two failed to leave the tubes. Only one of the seven launched made a hit and it broke apart and was used as a life raft by Japanese survivors of the dive bombing attack.
        A unacceptably larger number of torpedoes "prematured", that is, exploded on the way to the target. Because evading submarines could not see the results, any explosion heard near the target was assumed to be a hit. Later, when the submarine surfaced and found no ship, the assumption was that it had sunk, where it may have simply run away when warned by a premature. Credited sinkings were more than 50% greater than post-war confirmations and tonnage claimed was more than double that confirmed from Japanese records.
        Some sub skippers, suspicious of the torpedoes, set the depth shallower and made hits which confused the results, others deactivated the magnetic exploder to further confuse the issue. Orders were specifically reissued from headquarters to set torpedoes to run deep and to use the magnetic exploder. This was because the US torpedo was fairly light and not able to penetrate the side armor of a warship or sink a large merchantman, whereas a magnetic triggered explosion under the keel would break the back of a ship ... if it worked.
        The direction control could lock "hard over" so that the torpedo circled, coming back at the sub that fired it. Tullibee (SS-284) and Tang (SS-306) are sunk by themselves in this fashion. Others were able to dive under the returning torpedo. An extreme example of "friendly fire".

    Summary .
    In the first four months of the war, the 27 subs that comprised the Asiatic fleet sank only ten ships. Most skippers were replaced with more agressive men. Yet problems continued. On 1 August 1942, BuOrd finally conceded the Mark 14 ran deep. On 9 April 1943 "Tunny (SS-282) found herelf in an ideal position to attack aircraft carriers Hiyo, Junyo, and Taiyo. From only 880 yards (perfect, close range), 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. 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. Finally, in July 1943, Admiral Lockwood ordered his boats to deactivate the magnetic influence exploder." "Duds" -- torpedoes heard to hit but not explode -- were addressed in September 1943 when the first torpedoes with new contact pistols were sent to war. For fully half of the war, submariners, pilots, and destroyermen had risked their lives with faulty equipment.

    "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.

      Submarine :Surface :
      US Mark 10  US Mark XIV  Japanese Type 95         Mark 15Type 93 Long Lance
      Diameter :21 inch21 inch21 inch21 in24 inch
      Range :1-3/4 miles2-1/4 miles5 miles7-1/2 miles25 miles
      Speed :36 knots46 knots50 knots45 knots54 knots
      Explosive :500 pounds643 pounds893 pounds825 pounds1,058 pounds
    The Japanese submarine torpedo, Type 95, a down-sized Long Lance, was the same 21" diameter of the U.S. types. The Long Lance, or type 93 torpedo, was 24" dia. used with telling effect by cruisers and destroyers. Top speed was 54 knots (60 mph) , maximum range 50,000 yards (25 miles) , with a 1,058 pound (half ton) warhead. Pure oxygen fired the fuel giving high performance and little surface wake. ABDA warships that closed to gun range, but thought they were out of torpedo range, were surprised and assumed they had hit mines or that submarines were in the area.

    Japanese Kaiten Torpedo.     Late in the war, the man-guided Kaiten or "Heaven Shaker" suicide torpedo was developed from an extended Type 93 of 8 tons with 3,000 pound of warhead with a range of 43 miles. Beginning in November 1944, five submarines set out into the Pacific on Operation Kongo each with 4 Kaitens strapped on deck. One launched from I-36 at Ulithi on 11Jan'45 sank tanker Mississinewa (AO-59) fully loaded including over 400K gal of avgas. Another on 24July'45 caused Underhill (DE-682) to be scuttled off Luzon. Several other ships were damaged and caused concern among the U.S. forces, but the operation was generally unsuccessful costing 187 American lives vs. 948 Japanese sailors, mostly from eight mother subs that were sunk.

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    About this page: Torpedo - Dud torpedoes plagued submarine, destroyer, and air launched performance for the first year and a half of the Pacific War.
    Last updated on July 29, 2009 -- added Shortage thru Summary, Silent Victory by Clay Blair.
      September 8, 2006 -- expanded aerial torpedo.
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    Albert Einstein worked on torpedoes in 1943. His solution to premature detonation was to install two magnetic detectors : the forward one armed the torpedo, the rear one fired it.   I don't think this making of the torpedo more complicated was implemented.