There were at least three problems with the Mark 14 submarine launched torpedo.
How could these problems have gone unknown?
Mark 10 . 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
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".
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 15||Type 93 Long Lance|
|Diameter :||21 inch||21 inch||21 inch||21 in||24 inch|
|Range :||1-3/4 miles||2-1/4 miles||5 miles||7-1/2 miles||25 miles|
|Speed :||36 knots||46 knots||50 knots||45 knots||54 knots|
|Explosive :||500 pounds||643 pounds||893 pounds||825 pounds||1,058 pounds|