Torpedo solution

[dorn]

Relating to torpedo solution, target solution is not easily visible as we are not used trigonometry at all.





I will show it on 1914 torpedo tech which is quite high and torpedo has 37 knots for 4500 yards or
27 knots for 10000 yards.


Graps shows situation 2 ships with parallel course and maximum distance to have even target solution either for fast or slow torpedo mode for diferent speed.

As you can see the distance is quite short. The graph shows the firing angle and impact angle for longer range - slow torpedo mode.



You can easily seen just about 19 knots angle of firing and impact is 45 degrees which is certainly not ideal torpedo solution. For that distance is about 7000 yards but torpedo is running 658 s thus more than 10 minutes, quite a time to make small course correction.



With battleline speed of 20 knots (quite common in 1914) with torpedo setting on fast, you need to be within 3786 yards and there are still 216 s more than 3 minutes to do something about it. The angle of impact is 57 degrees so reasonable but still small course correction can evade incomming torpedo quite easily.







And it is parallel course. If target is in course away from you, situation worse quite rapidly.

You can see effect on target course in graph bellow. Same 1914 tech, target speed 21 knots.







The situation with crusiers going over 25 knots worse even more.


Just in 1904 tech if you try to torpedo enemy cruiser in parallel course with speed of 20 knots, you need to be within distance 358 yards to have torpedo solution at all.







If somebody wants to know some torpedo solution the enclosed file can be used.


Torpedo solutions.xlsx (54.18 KB)

[oldpop2000]

All of you might find this interesting and informative

DD_TorpedoAttack_DTB1943_compressed.pdf (718.34 KB)

[jwsmith26]

That's a rather brutal reality check on the effectiveness of torpedoes in WW1. I guess the takeaway is - get close.

[oldpop2000]

Nov 10, 2020 12:00:11 GMT -6 jwsmith26 said:

That's a rather brutal reality check on the effectiveness of torpedoes in WW1. I guess the takeaway is - get close.

At the Battle of the Java Sea, the Japanese launched two huge torpedo salvoes, consisting of 92 torpedoes in all, but scored only one hit, on Kortenaer. She was struck by a Long Lance, broke in two and sank rapidly after the hit. And this was with the best torpedo in the world, so yes, close is better. The range she was sunk at was 700 yards by Haguro.

[dorn]

There is another important issue with range and it is accuracy of datas used for calculation. 
There is need course of target, speed of target which is much more difficult to be accurate at longer range. 
Another thing is that in long range just small change of course or speed made torpedo hit quite imprabable. 

[oldpop2000]

Here is good link to submarine and torpedo documents - www.hnsa.org/manuals-documents/submarine-and-torpedo-fire-control/ - download the first one on the list, its informative.

There are other factors not discussed in many articles. Temperature of the water, salinity, currents etc. Thermal layers can change the speed and deflect the submarine in small degrees.

[broadsides]

The most immediate influence torpedoes had from the earliest days was the "every small ship a capital ship killer" effect on formations and battle lines. Most of what is being cited here is the perfect torpedo theory for submarines.  Surface ships depend to divergence (spread) to overcome target distance/speeds/maneuver difficulties.

Groups of small, fast ships like TB and DD could better influence battle line distances by making speed runs against closing vessels. Pursuit of fleeing formations could be hindered if the retreating side had an effective torpedo equipped screen to slow the enemy. In fog/mist/long nights areas of the North and Baltic seas (unexpected close encounters) a single coast patrolling ship with torpedoes was a more effective sentry against raiding cruisers trying to sneak close to harbors. While most given examples have been between warships moving faster and turning quicker, the historical best prey for torpedoes were slower moving and turning cargo ships. In game AI effects maintaining battle distancing (mid to long range gunnery) between opposing CA/B/BB forces should increase as torpedo range/tube numbers on mounts increase.  Surface ships will go with a 'good enough' solution and fire a spread as close of possible.  MTB/PT type ships get close and fire at the bow of the target.  IDK if the game actually shoots a spread from multi-tube mounts.

 Submarines try to get a better firing solution.

  In real world practice in the Pacific U.S. sub commander Richard O'Kane developed the constant bearing method. The TDC is set for a solution once target heading and speed is determined and the periscope is aimed for that bearing. When the aiming point crosses the bearing you shoot, knowing the torpedo is going right where you aim.

[jwsmith26]

broadsides : "IDK if the game actually shoots a spread from multi-tube mounts."

It does.

[BathTubAdmiral]

Nov 10, 2020 13:33:37 GMT -6 oldpop2000 said:

Nov 10, 2020 12:00:11 GMT -6 jwsmith26 said:

That's a rather brutal reality check on the effectiveness of torpedoes in WW1. I guess the takeaway is - get close.

At the Battle of the Java Sea, the Japanese launched two huge torpedo salvoes, consisting of 92 torpedoes in all, but scored only one hit, on Kortenaer. She was struck by a Long Lance, broke in two and sank rapidly after the hit. And this was with the best torpedo in the world, so yes, close is better. The range she was sunk at was 700 yards by Haguro.

You surely have a more reliable source for this then wikipedia, because the wiki tells a very different picture (GE does give more details than the EN version; NL, FR and IT are mostly worse than EN; I don't know about other languages, because I can't read those...). But then, this is only wikipedia ... let's see, maybe I can find the source.

Oh, wait, what about this: Battle of the Java Sea: 27 February 1942 by Vincent P. O'Hara

1. IJN torpedo attack was at 16:33-16:52 (full daylight, with both fleets doing the manoeuvers of a gun battle); 39 torps at a range of 6.5-11nm.

At 17:13 , DD Kortenaer was hit and the DD USS John D. Edwards, recorded that, "Kortenaer, about 700 yards (640 m) bearing 80° relative, was struck on the starboard quarter by a torpedo, blew up, turned over, and sank.."

2. IJN torpedo attack 17:48-18:07 (smoke screens, impaired visibility); 92 torps at a range of 3-9nm, no hits.

3. IJN torpedo attack at 23:22/23 (4 allied cruisers sighted 2 IJN cruisers at 23:02 at a range of  9nm); 12 torps at a range of 7nm, with both lines of ships on parallel course and exchanging gunfire.

Nachi fired 8 torps, hit Java at 23:34 with 1, Haguro fired 4, hit De Ruyter at 23:32 with 1.

Both cruisers sank.

[oldpop2000]

Nov 13, 2020 11:13:12 GMT -6 BathTubAdmiral said:

Nov 10, 2020 13:33:37 GMT -6 oldpop2000 said:

At the Battle of the Java Sea, the Japanese launched two huge torpedo salvoes, consisting of 92 torpedoes in all, but scored only one hit, on Kortenaer. She was struck by a Long Lance, broke in two and sank rapidly after the hit. And this was with the best torpedo in the world, so yes, close is better. The range she was sunk at was 700 yards by Haguro.

You surely have a more reliable source for this then wikipedia, because the wiki tells a very different picture (GE does give more details than the EN version; NL, FR and IT are mostly worse than EN; I don't know about other languages, because I can't read those...). But then, this is only wikipedia ... let's see, maybe I can find the source.

Oh, wait, what about this: Battle of the Java Sea: 27 February 1942 by Vincent P. O'Hara

1. IJN torpedo attack was at 16:33-16:52 (full daylight, with both fleets doing the manoeuvers of a gun battle); 39 torps at a range of 6.5-11nm.

At 17:13 , DD Kortenaer was hit and the DD USS John D. Edwards, recorded that, "Kortenaer, about 700 yards (640 m) bearing 80° relative, was struck on the starboard quarter by a torpedo, blew up, turned over, and sank.."

2. IJN torpedo attack after 17:48-18:07 (smoke screens, impaired visibility); 92 torps at a range of 3-9nm, no hits.

3. IJN torpedo attack at 23:22/23 (4 allied cruisers sighted 2 IJN cruisers at 23:02 at a range of  9nm); 12 torps at a range of 7nm.

Nachi fired 8 torps, hit Java at 23:34 with 1, Haguro fired 4, hit De Ruyter at 23:32 with 1.

Both cruisers sank.

I have the book by Vincent P. O'Hara and in fact he is a friend of mine and I have reviewed his books to assess accuracy. My source is Japanese Destroyer Captain by Tameichi Hara who was there, and actually was the developer of Japanese torpedo tactics.

[BathTubAdmiral]

Nov 13, 2020 11:24:17 GMT -6 oldpop2000 said:

I have the book by Vincent P. O'Hara and in fact he is a friend of mine and I have reviewed his books to assess accuracy. My source is Japanese Destroyer Captain by Tameichi Hara who was there, and actually was the developer of Japanese torpedo tactics.

Then maybe you want to check your sources.

Those 700 yards are the distance between allied ships, IJN and Allies never came that close to each other.

From the "Office of Naval Intelligence, "The Java Sea Campaign- Combat Narrative" www.ibiblio.org/hyperwar/USN/USN-CN-Java/USN-CN-JavaSea

and therein a quotation from the log of the Edwards, kept by Lt. William J. Giles, Jr.:

The Kortenaer, which was about 700 yards to starboard of the Edwards, was caught in the starboard quarter at 1713 by a torpedo which came from behind. (52) There was a "heavy, whitish explosion flinging debris 100 feet in the air. She heeled way over and yawed 90° to the right. She poised momentarily and then turned turtle and folded up like a jackknife so that bow and stern came together. The stern end sank at once and the bow within 50 seconds of the original explosion. Men were blown high in the air and several jumped into the water or scrambled up her side as she heeled over. No survivors could be seen in the water." (53)

(52) Survivors thought that their ship had been torpedoed by a submarine, as the Japanese destroyers were at rather long range at the time, but it is entirely possible that the torpedo was fired by a destroyer. The position was lat. 16°25' S., long. 112°08' E.

(53) From the log of the Edwards, kept by Lt. William J. Giles, Jr.

[oldpop2000]

Nov 13, 2020 11:27:10 GMT -6 BathTubAdmiral said:

Nov 13, 2020 11:24:17 GMT -6 oldpop2000 said:

I have the book by Vincent P. O'Hara and in fact he is a friend of mine and I have reviewed his books to assess accuracy. My source is Japanese Destroyer Captain by Tameichi Hara who was there, and actually was the developer of Japanese torpedo tactics.

Then maybe you want to check your sources.
Those 700 yards are the the distance between allied ships, IJN and Allies never came that close to each other.

I saw 16 more torpedoes spring into the water from Yukikaze and Tokitsukaze. At this I gave in and yelled: “Fire torpedoes!” Four other destroyers followed Amatsukaze’s lead. I calculated the chances of a hit. Very slim at 6,000 meters. Perhaps less than five per cent—3 hits out of the 72—I figured. How wrong this proved to be!


Rear Admiral Shoji Nishimura’s cruiser Naka and his seven destroyers arrived presently and also released 64 torpedoes. The enemy again swung 90 degrees, this time to the north, in an unorthodox, fantastic movement, and all 64 of these torpedoes were wasted. The enemy then took two more 90-degree turns and the whole column turned around in a thick smoke screen. Such tactics were not to be found in the Imperial Navy manual. I just stood and gaped.


Japanese cruisers Nachi and Haguro, trailing far behind the two destroyer squadrons, saw the enemy and turned around. At about 2000 hours they released 16 torpedoes at a range of 16,000 meters. The distance was too great. The Allied fleet again made a 360-degree turn, and all these torpedoes were also wasted. The enemy fleet sped at full steam southward toward Surabaya.


At 0053 Nachi released eight torpedoes and Haguro four at targets bearing 60 degrees to starboard. The enemy ships were 10,000 meters distant. Encountering a brief rain squall, the Japanese officers crossed their fingers and hoped. At 0106 the dark night was suddenly lit by a tremendous fire pillar to the southeast. A torpedo had hit cruiser Java amidship. Four minutes later there was another explosion in the Allied column, and De Ruyter burst into flames to burn like a match box. Sailors on the decks of Nachi and Haguro shouted “Banzai!” They leaped and danced and slapped each other on the back with joy.



Hara, Tameichi. Japanese Destroyer Captain (p. 76). Naval Institute Press. Kindle Edition.



Hara, Tameichi. Japanese Destroyer Captain (pp. 73-74). Naval Institute Press. Kindle Edition.



Hara, Tameichi. Japanese Destroyer Captain (p. 73). Naval Institute Press. Kindle Edition.

Here are  three quotes from Hara's book on the Battle of the Java Sea. That's all for me.

[BathTubAdmiral]

Sorry mate, are you trying to troll me?

6,000 meters = 6,562 yards = 3.2nm
10,000 meters = 10,936 yards = 5.4nm

Where did you find 700 yards in this?

The only 700 yards I can find in any account are those between the DDs Kortenaer and Edwards.

[oldpop2000]

Nov 13, 2020 11:45:07 GMT -6 BathTubAdmiral said:

Sorry mate, are you trying to troll me?

6,000 meters = 6,562 yards = 3.2nm
10,000 meters = 10,936 yards = 5.4nm

Where did you find 700 yards in this?

I never do such things as most of the members of this forum will tell you. Another source I have, is Empires in the Balance Japanese and Allied and Pacific Strategies to April 1942 by H.P. Willmott and another is Eagle Against the Sun by Ronald Spector. I also have AAR written at the time.

[BathTubAdmiral]

Again: Where are 700yards (640m, 0.35nm) given as the distance that the IJn DDs launched torps at?

Especially, as the allied crews thought they where shot at by submarines, as the IJN ships where barely visible at the horizon at times.
And yes, this is in the reports.