The Ship Model Forum

The LLTT was more hype than bite, it was known for 3 things, 1) Range, 2) Accuracy & 3) Warhead weight: 1&2) any unguided TT has an effective range of <1 km regardless of Max range. in-fact any range capacity beyond this is a wast. German U-boats operated at rages <750 m. The ocean is not 2D like everyone views it, waves are a constant effect except in very shallow waters. you not only have varying currents under the water that are un-accounted for in TT targeting but the waves themselves are a moving vertical curvature of the water. Firing an unguided TT at ranges beyond 1 km is like trying to shot pool on a trampoline while someone bounces a bowling ball on it. Any hits beyond that range were pure luck (or more like: ...umm...yea...that was my target over there...not this one over here where I was looking...really it was, I swear wheres my eraser for the log book. ) the force at Salvo Island ran up on 2 CAs sailing fat dumb and blind, fired their Starboard TTs (about 30 by my records - anyone have the exact #s) and only hit with 3, (2 on Canberra and 1 on Chicago) (note- 3) blew Chicago's bow off, the single WWII surplus 21"TT fired from HMS Conqueror Blew General Belgrano {USS Phoenix} in half - yes the had larger warheads but the extra explosives were generally a wast, 21" was more than up to the job) That's about 10% accuracy by my reckoning. I-19 fired 6 21" TT at Wasp and hit with 3 (2 more hit other ships - she fired at - I'm sure those were the targets) that's 50% accuracy.
The reason for the disparity is the missions. The US was defending the area (protecting Henderson Field and the supply ships from attack) so they were on-station there. If you look further south & east of the actual sound you will find Chicago, Hornet, Wasp, Juneau and several others that went down covering the sound or trying to make it back to repair yards. The Japanese were attacking an airfield. If you look north and west you will find even more Japanese ships that made it out of the sound but never reached base, or never made it to the sound in the first place. there was one Japanese Army battalion who refused to set foot on a Destroyer (Destroyers were considered defensive and less honorable) so they tried to reinforce Guadalcanal by landing ships instead of the "Tokyo Express" (which were converted WWI DDs). Only a handful of these troops made it to the island (by swimming). The commander committed seppuku.

GMG4RWF, you have a very unrealistic view of torpedo tactics. They call it a spread for a reason. None of the boats that fired a spread expected to hit with all shots. The idea was to blanket an area to account for minor deviations in the calculations and to allow for target maneuvering - and still get a couple of hits. 20-30% was considered good shooting. The IJN planned to blanket a distant area with dozens of torpedoes hoping to get a few of what was referred to as "browning shots" within a formation. That was why Kitakami and OI were rebuilt to launch the massive 20 shot broadsides. A damaged BB that has to turn back won't be in on the "decisive battle" the IJN expected to fight. Whittle the numbers down to what the IJN BB force can handle. The target doesn't have to be sunk (although that was a bonus), it just has to not be where the battle is. One characteristic of the Long Lance you haven't mentioned is the small wake it left. Most of those hit never saw the torpedoes coming. And they were hit from farther away than the allied ships thought possible. So at first, the allies thought they had hit mines because it couldn't possibly have been a torpedo. And if it was a torpedo, it must have some from some undiscovered sub that was working with the fleet. Anything except those surface ships I see on the horizon. The German U-Boats were more sparing with their shots because the smaller German boats carried fewer torpedoes overall and the resupply base was so far away past a gauntlet of sub killers. To be effective, they had to do more with each shot.

You also need to be careful about some of the numbers you throw out. The IJN force at Savo had a maximum available of 30 torpedoes that could have been launched from the starboard side. That doesn't mean that all ships expended all. Tenryu still had torpedoes left to hit Quincy, and her tubes were centerline without reloads. I am sure others retained a few as well.

Furthermore, the bulk of the Tokyo Express runs at Guadalcanal were done by the modern, front-line DD's. In many cases, the only concession to the cargo they were carrying was that they left the reload torpedoes at home as weight compensation. The limited number of "converted WW-I boats" were for the late stages or further up the Solomons chain.

I know exactly what a torpedo spread is, and about TT tactics, and their effectiveness. I also know that it was rarely done & very in-effective. During the 30s the US built the Mahan and Bagley class DDs for the same purpose, that's why they had quad racks on each-side, to fire 4-8 TT per side set to circle around forward and swarm the enemy from both sides. This use was found to be ineffective and wasteful which is why the US switched back to all-center-line racks. The TT was viewed at the time the way we view SSMs, Expensive, limited in #, difficult to replace and able to be lethal with a single hit. Most Captains fired each one singly aimed at a target, or fired single shots at multiple targets hoping to hit several targets at once. The Tactic of Blind-firing dozens of TTs into a general area just in the hopes that someone will sail threw them, (as with Z17 Diether Von Roeder) was almost never employed. even when dozens were fired, they were aimed at a given target (or targets) and spaced out (as with I-19 at Wasp) with the intent of correcting aim. The IJN was more liberal with their use but few other countries did so. even so they were very ineffective. At Truk, Katori and Maikaze both fired full spreads at the Iowa and NJ who were moving slowly providing NGSF (880 ft long targets) and not one of the 12 TTs found a mark, the US ships didn't even know they had launched TTs. One non-Japanese "spread" was the mentioned Z17 Diether Von Roeder at Narvik. She fired her full spread of 8 TTs out the narrow mouth of the harbor at close range, one TT approached the side of Hunter but passed under her keel the other 7 (despite narrow confines, calm water and 4 targets crowded together) came no-where near a target. in WWI nearly all warships carried TTs but few TT hits were made from surfaec ships, the BB-TTs were never in effective range of the enemy because they stood out at several miles firing their guns, that's why the US stopped putting them on BBs & CAs, they were better used as gun platforms. Best they could do was cause the enemy to turn away in fear of a (expensive) salvo.
And why they were never used operationally. they were a very interesting design but an in-effective one, relying on a very limited and poor weapon.
Actually they had underway resupply called "Milk Cows" that carried fuel and extra TTs for the U-Boats. The U-boats did fire salvos, all 5 TTs (including the aft) at the same time, but (as already mentioned) each TT was calculated to go after a different target in the convoy (1 fish 1 target).

They were never used operationally because the Jutland style decisive battle was never an option after Pearl Harbor. The massive torpedo salvos were ineffective against a carrier fleet that could sink the IJN well outside of the range of even the Long Lance. Would the pre-war tactic have been effective against a battleship fleet? We will never know. So many other designs and weapons ended up being a waste of resources in the war that actually occurred. No nation's fleet commanders proved to be clairvoyant enough to predict the type of war that WW-II in the Pacific became. Off Guadalcanal, I doubt that any USN sailors would have considered the Long Lance ineffective though.

Just to correct you, HMAS Canberra was torpedoed by the US destroyer USS Bagley, not the Japanese.

She may have been sailing "fat dumb and blind" but she did a much better job of reacting to the threat than any of the US cruisers, one of which did absolutely nothing and the other three, considering the battle that took place minutes before within plain sight, effectively did nothing.

I wasn't singling out Canberra - the entire fleet was FDB, USS Blue sailed less than 6 miles from the enemy, with radar (all-be-it 1st gen junk), and failed to see a thing, while the enemy had all their guns tracking her (how does a little DD get spotted while failing to spot a huge 10,000tn CA in lead of 4 more 8,000tn CAs?). Canberra's crew did well to keep her afloat, as long a they did, but Chicago also made a valiant and successful effort without a bow (basically the same primary damage as General Belgrano but with 61cm LL-TTs instead of 21").

When I first read this thread, I was not really sure of whether the Type 93 Torpedo was really all it was made out to be or not.

After now having read accounts of the war from both sides up to 1943 (made after the war), I am pretty sure that even though the weapon was impressive, I think the Japanese put too much faith in it.

If they had combined it with the submarine tactics and Strategies of the Germans or even the USN, I am sure that the weapon would have become the most feared weapon in the Pacific.

But the Japanese were so myopically fixated upon Warships, even with their submarine fleets, that they nearly completely ignored merchant shipping, save as targets of opportunity.

Had they sought to interdict the USN's supply of Australia more diligently, and also focused upon the USN's supply of Hawaii and the South Pacific Region, they might have made a greater impact with the weapon, where it could be fired at ranges where the subs could more safely hide from Merchant Fleet DEs than they could from the larger and faster warships they typically hunted.

The Japanese just seemed to have done so many things wrong during WWII after their initial successes due to their myopic focus upon a "Decisive Battle" strategy, which was an utter delusion.

MB

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I have never read an account of the accuracy/hit rate to be expected from very long ranged torpedo fire.

To a certain extent it is similar to long-ranged gun fire. The length of time the torpedo takes to arrive on target means that even a small error will result in a miss (in the case of a torpedo the "stealthiness" of the attack is offset by the huge time it takes to travel to the target.

Obviously the torpedo only has to intersect a certain "ship length" rather then be totally accurate for range, but an error in range will mean that the predicted intersection point is wrong.

Has anyone ever done a mathematical study of the accuracy requirements for a successful very long-ranged torpedo attack versus the accuracy of Japanese range-finders, torpedo directors and torpedo gyros ?

I.E. what was the theoretical hit rate of a Long-Lance ?

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From what little I have read on the subject, the Japanese overestimated their hit-rates for the Type 93.

They were expecting one torpedo out of a spread of a typical DD Spread of 12 to hit, or 2 - 4 to hit out of a DD Group's Spread of 20 - 40 torpedoes.

I know that in reality, aside from Savo Island, and a couple of other battles in the Guadalcanal Campaign, they typically missed completely with long range Torpedo salvos.

It was only massed salvos at under 12,000 years that they achieved any success at all.

I can't give numbers, but that is the conclusions of a book I just read of accounts of IJN Officers interviewed after the war.

MB

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