From duds to lethal, the Mark 14 torpedo was troublesome at first for American submariners.
By Mark Carlson
Lieutenant Dan Daspit, captain of the U.S. submarine Tinosa might notbelieve his luck. Framed neatly within the periscope eyepiece was a sitting duck. The 19,250-ton Japanese tanker Tonan Maru No. three was on their lonesome, lifeless within the water. Tinosa was on her second struggle patrol, having left Halfway atoll on July 7, 1943. For every week she had been prowling alongside the Japanese sea routes between Borneo and Truk. On the afternoon of July 24, Daspit noticed a skinny path of grey funnel smoke on the horizon. Remaining submerged, he arrange a textbook strategy and fired 4 Mark 14 torpedoes on the ship, which was making solely 10 knots. Each considered one of his “fish” ran true. Thirty seconds later, the sonarman heard the repeated thumps of the torpedoes hanging the hull, however no explosions. The tanker turned and elevated velocity.
Swearing, Daspit turned in pursuit. After an extended nighttime chase, he was in place to attempt once more. His torpedomen checked each fish to ensure it was working completely. Then, coming on the tanker from the starboard quarter, he fired two extra torpedoes. Each hit and exploded. The muted rumble echoed by means of Tinosa’s hull. The crew cheered.
The Tonan Maru had been hit within the engine room and coasted to a cease. An skilled submarine commander, Daspit took his time approaching the ship’s port aspect. He would hearth one torpedo at a time from 1,000 yards, aimed to strike the tanker’s hull at precisely 90 levels. The 680 kilos of high-explosive Torpex would blast an enormous gap within the hull. Two or three fish ought to ship her to the underside. The tanker couldn’t run. Tinosawas going to hold the large Tonan Maru’s scalp on her belt.
At 0930 hours, Tinosa fired her first torpedo. It ran straight and true. The wake was an extended lethal white finger reaching out to the touch the helpless ship. Then nothing occurred. The torpedo had did not explode. This was nothing new to the American submarine fleet, so Daspit fired once more. No towering column of water erupted from the tanker’s hull. No crushing roar echoed via the deep.
Gritting his tooth in frustration, the sub’s skipper fired once more. And once more. 5, then six lethal Mark 14 torpedoes, probably the most superior antiship weapons within the U.S. stock did not explode. The fifth one appeared to boost a tall plume of white water as a tinny “Phwyinng!” noise got here via the hull. Quantity six broached and leaped after hanging the enemy’s hull, then sank.
Then the tables turned. The Tonan Maru had radioed a misery name. A Japanese destroyer was coming with a bone in her tooth. Tinosa needed to depart the world quick.
Daspit fired two extra torpedoes on the tanker as his submarine turned away. The sonarman reported that each weapons appeared to hit after which cease.
As his sub raced eastward, Daspit wrote of the irritating hunt in his log. “I discover it onerous to persuade myself that I noticed this.” He had no rationalization for why the torpedoes did not explode. Out of 15 Mark 14s fired, solely two had detonated, and people had been fired from what was thought-about to be a really indirect angle. The others have been so rigorously arrange as to be proper out of the textbook. But not one had completed its job.
Daspit headed immediately again to Pearl Harbor doing what no American sub skipper ever needed to do, returning with an “empty bag.” He was met on the Sub Pier by the brand new Commander, Submarines, Pacific (COMSUBPAC), Rear Admiral Charles Lockwood, a profession submarine officer. Lockwood was a hard-driving, conscientious officer who had the popularity for giving full help to his squadrons, his boats, his commanders, and their crews. He took Daspit as much as his workplace the place the exasperated sub skipper associated what had occurred with the Tonan Maru.
Lockwood listened, nodding. He later wrote, “I anticipated a torrent of cuss phrases, damning me, the Bureau of Ordnance, the Newport Torpedo Station and the bottom torpedo store. I couldn’t have blamed him. 19,000-ton tankers don’t develop on timber. I feel Dan was so livid as to be virtually speechless.”
However when the only torpedo Tinosa had introduced again to Pearl was examined on the Submarine Base torpedo store, it was discovered to be in good working order.
Lieutenant Commander Daspit’s report was the newest and excessive case of what had been a rising drawback inside the U.S. submarine fleet because the starting of the warfare. From the primary patrols after the Commander-in-Chief U.S. Pacific Fleet (CINCPAC), Admiral Chester Nimitz, had ordered unrestricted submarine warfare on all Japanese delivery, submarine commanders had been complaining of torpedoes that did not work correctly. On December 14, one week after Pearl Harbor, the united statesSeawolf encountered a Japanese freighter close to the Philippines and fired eight torpedoes. Seven missed, one hit. And did not explode.
So started the litany of issues with the Navy’s technical marvel. Within the first months of conflict, American subs fired 97 torpedoes at enemy delivery. Solely three ships have been sunk. Some did not explode, whereas others, regardless that aimed with care, appeared to overlook or run beneath their goal. Even worse, a number of had blown up earlier than hitting the aspect of a Japanese ship.
Torpedoes have been the primary completely autonomous guided missile. The German Navy had sunk lots of of Allied ships in World Struggle I with torpedoes, and by 1925 the newest variations have been extremely complicated machines. The Mark 14 was developed to switch the older, shorter Mark 10 that had been in service throughout and after World Warfare I.
Designed primarily by engineers on the Navy Bureau of Ordnance (BuOrd), the Mark 14 was constructed on the Newport Torpedo Station (NTS) starting in 1926. At 21 ft lengthy, 21 inches in diameter, and weighing greater than three,000 kilos, the Mark 14s have been giant and costly weapons. Powered by steam, they might run for 9,000 yards (5.1 miles) at 46 knots. They have been extraordinarily complicated and required probably the most meticulous machine and meeting work. By 1940, they value upward of $10,000 every, 5 occasions as a lot as a brand new vehicle.
An important element was the Mark 6 exploder, with out which the torpedo can be ineffective. The sure approach to sink a ship was to interrupt its again on the keel. This typically induced a ship to interrupt in two. Clearly, this required a torpedo to blow up underneath the hull. To this finish BuOrd had designed the brand new exploder based mostly on the profitable British Duplex and German magnetic mine designs. Its most radical function was the magnetic affect exploder, Venture G53. It was a intently guarded secret, a lot in order that despite the fact that a upkeep and working guide had been written it was by no means printed or distributed.
The magnetic exploder was triggered by the affect of a metal hull because it handed immediately beneath a ship, the place there was no armor. Because of this, the primary Mark 14s carried a average warhead. BuOrd was underneath a decent finances and noticed no cause to spend cash on pointless testing. Just one check of the Mark 6 was carried out in Might 1926. The goal, mockingly, was a derelict submarine. Two Mark 14s armed with the magnetic exploder have been fired on the sub. One ran beneath the goal and did not detonate. The second exploded and sank the sub. What was not being taken under consideration have been variations within the Earth’s magnetic subject. The Mark 6 was extremely delicate and too more likely to detonate with even minor fluctuations. This was not thought-about a flaw, and in 1934 the Mark 6 was accredited for fleet use.
No additional testing was finished. The U.S. submarine pressure went into fight with a torpedo with a 50 % failure price.
In 1939, the Navy demanded a bigger warhead, and BuOrd approved its improve to 680 kilos, sufficient to tear open probably the most sturdy hull. However, as occasions proved within the first yr of the struggle, the magnetic exploder labored too properly. A number of sub skippers fired at their targets solely to witness untimely detonation nicely earlier than the torpedo was shut sufficient to do critical injury. Typically the enemy ship suffered little greater than dented plates that have been simply repaired.
The Mark 6 additionally had a contact exploder, which consisted of a set off, firing pin, and detonator. In essence it was not a lot totally different from a gun’s set off, firing pin, and the primer in a cartridge. When the torpedo struck a ship’s hull, the top was rammed backward, driving the firing pin into the detonator over the warhead, inflicting it to blow up. The contact exploder was meant to offer a backup within the occasion that the magnetic pistol did not work. However because the warhead exploded even earlier than contact with the hull, it was ineffective.
By mid-1942, greater than 800 torpedoes had been used within the Pacific Warfare. Eighty % had failed. However at Pearl Harbor, COMSUBPAC Admiral Robert English persistently sided with BuOrd and blamed his sub skippers for his or her “lack of initiative.” However the man who would quickly change every part, Rear Admiral Charles Lockwood, then commanding submarines within the Southwest Pacific and based mostly in Australia, was listening to his personal submarine skippers. He undertook an unofficial check of the torpedoes in June 1942.
Lockwood supervised firing torpedoes set to particular depths via a submerged internet. This was the primary actual check of the Mark 14 since 1926. The holes within the internet confirmed that the torpedoes have been operating far under the set depth, typically as a lot as 10 to 15 ft. This was conclusive proof, however once more BuOrd dismissed the findings and stated the submarine commanders weren’t trimming the torpedoes correctly.
Lastly, underneath strain from Admiral Nimitz, himself a former submariner, BuOrd carried out its personal checks in August 1942. The basis of the depth-setting drawback had been the fault of BuOrd. Once they elevated the dimensions of the warhead, which made the weapon heavier, they did not make modifications within the mechanism that managed depth.
But the erratic depth was solely one in every of three main issues with the torpedoes. Dozens of torpedoes have been exploding properly earlier than reaching the goal. The trigger was the hypersensitive magnetic exploder. It was being triggered by a mixture of the Earth’s magnetic area and the strategy to a ship’s hull. These issues ought to have been discovered and glued lengthy earlier than the conflict started.
Rear Admiral Lockwood was appointed COMSUBPAC in January 1943. When his captains turned in quite a few studies of untimely explosions or duds, BuOrd steadfastly maintained that there was nothing incorrect with the torpedoes, however that the issue lay with dangerous approaches and poor upkeep. This naturally began a furor among the many submarine fleet personnel. U.S. sub crews have been risking their lives for nothing. The transports and warships of the Imperial Japanese Navy sailed on, unmolested.
Lockwood requested permission to disconnect the magnetic exploders on the torpedoes, however BuOrd wouldn’t permit it. The submarine crews have been forbidden to do something past common upkeep to the torpedoes. They have been to not contact the Mark 6 exploders. To stop any unauthorized tampering, BuOrd ordered that the Sub Base torpedo store apply dabs of paint to the screws that held the exploder mechanism to the torpedo physique. Any try and take away or tamper with it will mar the paint. With the zeal that American army males typically take when going towards orders, some torpedomen went into the store and requested concerning the colour of paint. In the event that they have been advised it was blue, they discovered a small can of blue paint to retouch the screw heads after that they had personally labored on the exploders. Within the occasion a torpedo was returned to the store, there was no method for anybody to know the mechanism had been touched.
Because the variety of duds and untimely explosions rose, there might be little question one thing needed to change. In the summertime of 1943, Lockwood flew to Washington and defended his skippers to BuOrd, demanding that one thing be completed. In June, beneath strain from the Chief of Naval Operations (CNO) Admiral Ernest J. King, the order got here right down to disconnect the magnetic exploders from all of the torpedoes. When the Tinosa left Halfway on her second patrol this had been carried out. Lt. Cmdr. Daspit had each purpose to consider his load of Mark 14s would do the job. This proved to be a forlorn hope. Whereas the Tinosa’s patrol was not the incident that broke the camel’s again, it was probably the most appalling. The complaints continued to mount. Lockwood’s employees started a scientific examination of the issue.
That’s when Lockwood took private motion. As a way to persuade BuOrd that the issue was not together with his subs, skippers, or crews however with the torpedoes, he referred to as in Commander Charles B. Momsen. “Swede” Momsen, whose outspoken behavior of going towards the official grain had earned him few buddies within the Pentagon, was one of the revolutionary submarine engineers within the Navy. He had overseen the rescue of the crew of the united statesSqualus after it sank off Portsmouth, New Hampshire, in 1939. He was the inventor of the Momsen Lung, the moveable respiration gadget that saved tons of of submariners from sunken subs. He was additionally the daddy of the submarine rescue chamber that had develop into a part of the Navy stock since 1939. The fashionable submarine Navy owes the lives of lots of its males to Swede Momsen.
Momsen was in control of Submarine Squadron (SubRon) 2. Even after the BuOrd order, the reviews of dud hits continued to pour in. Momsen, who needed to endure the frustration of his skippers carrying ineffective torpedoes all the best way to Japan for nothing, started to use his engineer’s thoughts to the answer.
Step one was to seek out out why the contact exploder didn’t work, even when fired beneath optimum circumstances. He scoured charts of the waters across the Hawaiian Islands to discover a place the place sheer vertical cliffs went proper right down to deep water and a sandy backside the place torpedoes could possibly be recovered after firing. An space on the coast of the small island of Kahoolawe was good. Momsen, together with COMSUBPAC’s gunnery and torpedo officer, Commander Artwork Taylor, supervised reside firings from the united statesMuskellungeat the cliffs starting on August 31.
The primary two exploded. The third one didn’t. Momsen himself went into the water to look at the torpedo. It was damaged in two with the warhead cut up. Taking excessive care, the crew hoisted the unexploded torpedo onto a barge and took it again to Pearl Harbor. After disconnecting the warhead, Momsen and his crew discovered the rationale for the failure. The contact exploder, whereas a marvel of engineering, was each too ruggedly constructed and too delicate.
This was additional studied by sliding a torpedo warhead full of sand and a reside exploder down a cable from a 90-foot “cherry picker” crane onto a metal plate to simulate totally different angles and speeds of impression. Seventy % of the hits did not explode.
This additional proved what Momsen had begun to suspect. Submarine commanders had been advised that the perfect and most sure angle to fireside a torpedo at a goal was from precisely 90 levels, or broadside on. Acute angles have been much less fascinating. However as was proven by Tinosa’s expertise, this was not true. Daspit had fired eight torpedoes at precisely 90-degree angles and never one had gone off. Sarcastically, the primary two he had fired that morning after the lengthy chase each detonated, despite the fact that they struck the tanker’s hull at a really indirect angle.
Momsen and Taylor realized that the contact exploder’s firing pin was being distorted in a head-on impression, and the deceleration forces slowed the pin’s movement in its bearings. The spring failed to maneuver it quick sufficient to set off the explosive cost. Examination of the primer confirmed hardly a dent, not almost sufficient to ignite the warhead.
The drop check confirmed that a glancing influence did permit the firing pin to behave correctly. In different phrases, the most effective angle to fireside was something aside from lifeless on.
Apparently, BuOrd had made a small try to seek out the basis of the issue by consulting Albert Einstein at Princeton College. The distinguished physicist examined the Mark 6 blueprints and concluded that the firing pin was being distorted by the influence. He advisable that a “void” between the outer shell and the firing mechanism would remove the issue. However BuOrd didn’t comply with his suggestion. Momsen confirmed the check outcomes to Lockwood, who then took them to Washington. He returned a couple of days later, as he stated in his official warfare diary, “madder than hell.” BuOrd lastly admitted the exploder was at fault and dedicated to designing a brand new one. However that might take a yr or extra.
Then Momsen advised Lockwood that it must be potential to rebuild the contact exploder with totally different supplies. The exploder needed to be each mild and powerful. Unique alloys proved to be the important thing. The machine store on the Sub Base obtained mild alloys, from, remarkably sufficient, the melted-down engine of a Japanese fighter that had been shot down through the Pearl Harbor assault. New firing pins, springs, and information tracks have been machined and assembled. The brand new designs have been examined and carried out precisely as hoped. But, the challenge wanted much more metallic than one engine might present. One other supply was discovered at Hickam Military Airfield. Plane propellers needed to be each mild and powerful. One Military Air Forces officer supposedly stated after being requested for as many broken propellers as he might discover, “A greater use for a busted prop couldn’t be discovered anyplace.”
Lockwood insisted on each single new exploder being good earlier than permitting them to be put in within the torpedoes and loaded into his submarines. With each machine store on the Sub Base engaged on it, by the late fall of 1943 the Pacific Fleet’s submarines have been lastly armed with dependable weapons.
Underruns have been nonetheless a priority. Taylor and Momsen once more supervised exams. Firing torpedoes via a collection of evenly spaced nets confirmed that not solely have been the Mark 14s operating properly under their set depth; they weren’t even operating flat. They appeared to wobble, like a sine wave, alternately deep and shallow. This was not one thing that might be fastened at Pearl Harbor. It must go proper to BuOrd. However at the least Lockwood’s skippers might make allowances for the erratic depth settings.
When the primary dependable torpedoes have been despatched to sea, the warfare had been happening for 21 months. Of the 53 U.S. subs misplaced in World Conflict II, 20 have been sunk previous to October 1943. There isn’t any strategy to know if any have been misplaced as a result of defective torpedoes, however there might be no larger frustration than to die with out having been capable of inflict injury on the enemy. Dozens of patrols had been wasted, a whole lot of American lives misplaced, and necessary enemy targets missed. Finally the issue for the submarine commanders was what it ought to have been from the start: hitting the goal. As Lockwood put it, “From that second on, all main exploder issues all of a sudden disappeared.”
Momsen was promoted to captain and awarded the Legion of Benefit for locating and fixing the torpedo drawback. He had performed a big however little remembered position in assuring that each U.S. submarine went to warfare towards Japan with dependable torpedoes. By August 1945, 1,178 Japanese service provider vessels have been sunk, totaling 5,zero53,491 tons. Of these, 55 % have been despatched to the underside by U.S. submarines.
Writer Mark Carlson has written on quite a few subjects associated to World Warfare II and the historical past of aviation. His guide Flying on Movie—A Century of Aviation within the Films 1912-2012 was lately launched. He resides in San Diego, California.