John P. Cromwell attack technique on order

[Rockin Robbins]

I was having an extended PM conversation with Nisgeis about targeting methods. He had a great idea about shooting from 45º ahead of the target to increase the speed of the torpedo relative to the target compared to the right angle approach of the Dick O'Kane method. His spider senses told him that the 45º attack might be as easy to deliver as a Dick O'Kane attack and come with a bunch of advantages. He could just about see how the thing would work, but couldn't quite put it all together. Does he ever have great instinct. His attack method is a gem!

In addition to the torpedo's speed, 70% of the target's velocity is helping bring them together more quickly!

Therefore for a shot taken at the same range the target gets much less time to react!

If for some unknown reason you blow the attack and the target is still 45º in front of you, you have time to set up another Dick O'Kane attack before he gets to you!

In a convoy situation an angled shot through the columns might miss your target, but has maximal chance of picking up another victim!

All that made me really curious. So I broke out MoBo--electronic maneuvering board and salad slicer. Shazzam! There appeared to be a way to make this work as easily as Dick O'Kane, with no outside tools or calculator necessary. Nisgeis wanted to call it Fast-45, but I hit him with aaronblood's true (damn! his arguments are ALWAYS true:nope:) contention that Fast-90 was a technique that required the U-Boat's periscope/TDC direct connection and calling this Fast-45 would just muddy the water.

The Dick O'Kane technique is named after a great submarine ace, who used similar but not exact TDC wizardry to bring down his targets. Why not continue to name these after great American sub commanders? Our list came down to two commanders, but one, John P. Cromwell, merited the name for several reasons. First, he never had the chance to use this technique. He died without notable success in destroying the enemy. But he received the Congressional Medal of Honor for a very special reason. While attacking a Japanese convoy on 19 November 1943, Sculpin was forced to the surface, fatally damaged in a gun battle and abandoned by her surviving crew members. Captain Cromwell, who knew secret details of the impending operation to capture the Gilbert Islands, deliberately remained on board as she sank. And quoting his subsequent Congressional Medal of Honor citation:
Determined to sacrifice himself rather than risk capture and subsequent danger of revealing plans under Japanese torture or use of drugs, he stoically remained aboard the mortally wounded vessel as she plunged to her death. Preserving the security of his mission at the cost of his own life, he had served his country as he had served the Navy, with deep integrity and an uncompromising devotion to duty.
So this attack technique will be a tribute to a true hero, who never got his chance to show his skill in a way that would make his name memorable today. But perhaps by naming an attack technique designed for a game, which itself memorializes the men who served, after this man, we might pause, while setting up this attack, to remember John P Cromwell, whose deed was every bit as heroic as those we celebrate: Mush Morton, Dick O'Kane, Sam Dealey or Eugene Fluckey. Let's remember Captain Cromwell as we set up this attack, named for him.

With the help of MoBo I've worked out the math and reduced its complexity so you can figure it out in your head in real time during the game. I've executed one practice attack, hitting four of four from 3300 yards. So it works.

Now the hard part: writing a set of instructions that YOU can use even better than I can, and making a tutorial movie for those who don't learn from written instructions. I can't make any promises on time. It's more important to do this right than do it on a schedule. I can tease you with my attack setup from the nav map on the prototype attack:
http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/John%20P%20Cromwell%20Tech/SH4Img2008-10-19_154705_046.jpg

I could show you the picture of the tanker exploding, but that would just be bragging. I try not to do that, but to teach others to jockey their subs, hopefully better than I can. You can post your own explosions when this thing gets off the ground.:up:

[Lexandro]

Nice post RR. As it transpires this kind of attack is how I have been approaching the game with Monsun/RSRD due to the large size of the convoys. By coming in at a 45 degree attack angle I can work a position to fire my bow and stern tubes in one flurry, using the targets forward speed as an "assist" to the torpedo travel time. That way I can hit 2 targets in one attack run and if I continue on my path I can work another shooting oppertunity from the convoy moving across my path.

While it would be much harder to do with full manual aim (ie work 2 sets of TDC calcs) the 45 degree attack angle method is a staple in my play book.

[Rockin Robbins]

Lexandro, all my attack techniques are manual targeting techniques with the goal of making them so easy and enticing that you, on your next trip to port, will x that manual targeting option and go for it!

Even though it's cool to take out all the escorts and shoot multiple targets with auto-targeting, there is nothing to compare with all the whooping and hollering that takes place when you take out your first target on manual targeting.

My wife thought I was an idiot! Why does she have to be right all the time? It isn't fair....:oops:
http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/John%20P%20Cromwell%20Tech/SH4Img2008-10-19_154334_546.jpg

[SteamWake]

Nice post RR. As it transpires this kind of attack is how I have been approaching the game with Monsun/RSRD due to the large size of the convoys. By coming in at a 45 degree attack angle I can work a position to fire my bow and stern tubes in one flurry, using the targets forward speed as an "assist" to the torpedo travel time. That way I can hit 2 targets in one attack run and if I continue on my path I can work another shooting oppertunity from the convoy moving across my path.

While it would be much harder to do with full manual aim (ie work 2 sets of TDC calcs) the 45 degree attack angle method is a staple in my play book.

I too have been approachin at a similar angle... just made sence to me. As you said if you miss you still have an easy correction to fire again. Plus the closing angles of the torp and the intended target..... well just makes sense its faster.

Ive been doing this out of 'instinct' its pretty cool so see my guesses confirmed. :rock:

[Lexandro]

Usually I try the full realism settings in a sim game and can get to grips with the after a bit of practice. In falcon 4.0 I have mastered the full realism settings of air-combat in an F-16 and I know exactly what every button and switch does and when and how to use it.

In SHIV however, its less instinctual than say flight is. Its more calculatory based combat, and to be frank I really cant get to grips with doing lots of math just to play the game. No doubt as some point I will get my head around it in a simple fashion, its just that for the time being manual aim is beyond my grasp.

If there was a proper tutorial mission just for working an easy shot, with lots of guide and tips on how to do so in the mission itself I might be able to learn it easier. Doing it hands on its a much more powerful learning tool for me than learning from study.

[Rockin Robbins]

Nisgeis, why don't you pop in here and tell your story of how you thought up this attack method and what you told me that made me wrestle with all those nasty numbers?

[XLjedi]

So, I see you're coming in on a 45° to the target TC.

Is that it? ...or is there something more to it? :hmm:

So far, I'm not really seeing any need to name it anything... :-?

[Rockin Robbins]

Aaronblood, not to be sarcastic (on the other hand, why not?:arrgh!:), but there is one reason to name anything. Human beings have a weird psychological need to label things. Sometimes we even conclude that we know the name of something, so that means we understand it.

You're looking at a strange looking animal you've never seen before. "What in hades is that?" you say. "It's a flobberbitimous compressiceps" I say. You're perfectly happy, although you know nothing more about that strange looking animal than you did a minute ago.:rotfl:But you can tell your girlfriend you saw a flobbergitimous compressiceps and she will get that serious look that tells you she's impressed.

But more than anything names are handles for a collection of behavior directed at a desired goal. How do you find the location of a submarine by listening to it from two radio receivers? Triangulation. The word is shorthand for a complex procedure, usually performed by a team of different people.

In a similar manner, Dick O'Kane attack is a handle for a collection of actions including a course at right angles to the track, AoB being equal to 90º minus the number of degrees from the shoot bearing to zero bearing, turning the position keeper off, yada, yada, yada. I can say, do a Dick O'Kane attack here and you know the steps to take.

John P. Cromwell Attack will be the same kind of handle, encompassing a specific sequence of steps including a course at 45º from the track from ahead of the target, AoB being 45º minus the bearing, position keeper off, yada, yada, yada.

We name things because that is how our brains work. It helps us to remember. In these two cases they also help us to remember great submarine captains of World War II. Every time we pull off one of these tactics we remember them.

What could be bad about that?:up:

[Nisgeis]

So, I see you're coming in on a 45° to the target TC.

Is that it? ...or is there something more to it? :hmm:

So far, I'm not really seeing any need to name it anything... :-?

I never really understood the Dick O'Kane method. I could never relate the instructions to the maths behind the technique. It just seemed a bit like a rough guess, which worked because you were very close to the target. I had a look on your tutorial thread, but that's a very brief snippet talking about a 7 knot target, with no details. Can you point me to the log behind it?

This new method came out of me trying to create a rule of thumb for a 45 degree attack, without using the TDC at all. I thought the Dick O'Kane method was a non TDC method to attack a target with a zero gyro angle, but it turns out the TDC is used and is more complicated that I thought.

My aim is to present a simple method people can use who want to do manual targetting, but don't want to use the TDC.

As it happens, I could not get an easy rule of thumb for 45 degree attack and after investigating, I found that the old speed plus three rule of thumb is also not satisfactory at all. I came up with a way to get the correct bearing of the target to fire at to hit with any torpedo track angle, with a zero gyro angle, by just using the map drawing tools. Just one protractor drawing and two rule drawings are enough to easily calculate the correct lead angle for a zero gyro angle shot at any intersecting courses for any given target speed or torpedo speed. It's essentially a constant bearing solution for torpedo and target, making the range irrelevant.

[SteamWake]

But the bearing is not constant due to the targets speed and its AOB also any movement by your own boat.

[Nisgeis]

But the bearing is not constant due to the targets speed and its AOB also any movement by your own boat.
Constant bearing, decreasing range is when two objects are on a collision course. The bearings of the two objects relative to each other stay constant and the range closes, until it reaches zero and you have a collision. The two objects will always collide, making range irrelevant.

[Rockin Robbins]

There are three main methods of using the periscope to shoot torpedoes:

The check bearing method, where you take a series of quick observations to set up and confirm TDC inputs. Each periscope exposure is as short as possible . The periscope bearings are checked against the TDC to predict a good solution. We can do this and most do in Silent Hunter 4.

The continuous bearing method, where the periscope operator keeps the scope up and the assistant periscope operator calls out the bearings continuously to be entered into the TDC to keep it continuously updated during the firing of torpedoes. We can't really do this one. I suppose we could stab the send bearing/range button every several seconds, but that would reset the range to the last one we measured with the stadimeter.

Finally, the constant bearing method. Here the TDC is set for a predetermined solution. The periscope is aimed at the bearing determined by the solution and held on that constant bearing. As juicy parts of the target cross the wire you send fish their direction. All torpedoes follow the same path to the target in a longitudinal spread. The Dick O'Kane technique is a constant bearing technique, as is the John P Cromwell.

So with the constant bearing method the only thing constant is the bearing on which you hold the periscope.

It is true that from the point of view of the torpedo the target maintains a constant bearing until collision, but that is a factor shared by all three shooting methods and is irrelevent to the discussion.

Comprendé?

[kiwi_2005]

Aaronblood, not to be sarcastic (on the other hand, why not?:arrgh!:), but there is one reason to name anything. Human beings have a weird psychological need to label things. Sometimes we even conclude that we know the name of something, so that means we understand it.

You're looking at a strange looking animal you've never seen before. "What in hades is that?" you say. "It's a flobberbitimous compressiceps" I say. You're perfectly happy, although you know nothing more about that strange looking animal than you did a minute ago.:rotfl:But you can tell your girlfriend you saw a flobbergitimous compressiceps and she will get that serious look that tells you she's impressed.



:rotfl::rotfl: :up:

[peabody]

(refering to Nisgeis) Does he ever have great instinct.

Yes, he does!! I think I understand the consant bearing, decreasing range concept. I think I understand where you are headed, but don't have any idea yet how you are going to get there, eargerly awaiting that part. :hmm:

Just for discussion purposes , isn't a 45 degree shot going to cause problems with duds? In the torpedo .sim file the dud chance is 1% at 0 to 35 degrees, but from 35 degrees to 70 degrees it increases to 35%. (Unless I misunderstand the data.)

Peabody

[Rockin Robbins]

(refering to Nisgeis) Does he ever have great instinct.
Yes, he does!! I think I understand the consant bearing, decreasing range concept. I think I understand where you are headed, but don't have any idea yet how you are going to get there, eargerly awaiting that part. :hmm:

Just for discussion purposes , isn't a 45 degree shot going to cause problems with duds? In the torpedo .sim file the dud chance is 1% at 0 to 35 degrees, but from 35 degrees to 70 degrees it increases to 35%. (Unless I misunderstand the data.)

Peabody

:damn::damn::damn::damn:Well, I have good news and I have bad news. The good news is that the attack method works fabulously, both using the TDC and not using the TDC and I'll teach it both ways at once! The bad news is I'm about the worst movie maker in history and I screwed up four takes in a row tonight for technical reasons. I have put 16 of 16 torpedoes into various targets. This is just as deadly as Dick O'Kane and just as easy.

I spent a lot of time trying to talk Nisgeis out of drawing triangles on the nav map to aim the torpedo, tried it myself and I love it! It does require you to keep several pieces of information straight, but if your TDC ever breaks and you can keep your facts straight, you'll never miss the missing TDC.

Some might say that a 45º shot might not be as accurate as a 90º shot because of the lesser error tolerance and the smaller angular size of the target. Don't believe it. I hit 4 of 4 at 3000 yards with no problem.

But I don't have a good tutorial movie yet. Tomorrow will have to do. I think you'll enjoy it. It will be so simple that most of you will be better at it than I am in 24 hours. But I can't believe it. I filmed and talked myself silly for two hours and have nothing to show for it!:damn::damn::damn::rotfl:

[Orion2012]

(refering to Nisgeis) Does he ever have great instinct.
Yes, he does!! I think I understand the consant bearing, decreasing range concept. I think I understand where you are headed, but don't have any idea yet how you are going to get there, eargerly awaiting that part. :hmm:

Just for discussion purposes , isn't a 45 degree shot going to cause problems with duds? In the torpedo .sim file the dud chance is 1% at 0 to 35 degrees, but from 35 degrees to 70 degrees it increases to 35%. (Unless I misunderstand the data.)

Peabody
:damn::damn::damn::damn:Well, I have good news and I have bad news. The good news is that the attack method works fabulously, both using the TDC and not using the TDC and I'll teach it both ways at once! The bad news is I'm about the worst movie maker in history and I screwed up four takes in a row tonight for technical reasons. I have put 16 of 16 torpedoes into various targets. This is just as deadly as Dick O'Kane and just as easy.

I spent a lot of time trying to talk Nisgeis out of drawing triangles on the nav map to aim the torpedo, tried it myself and I love it! It does require you to keep several pieces of information straight, but if your TDC ever breaks and you can keep your facts straight, you'll never miss the missing TDC.

Some might say that a 45º shot might not be as accurate as a 90º shot because of the lesser error tolerance and the smaller angular size of the target. Don't believe it. I hit 4 of 4 at 3000 yards with no problem.

But I don't have a good tutorial movie yet. Tomorrow will have to do. I think you'll enjoy it. It will be so simple that most of you will be better at it than I am in 24 hours. But I can't believe it. I filmed and talked myself silly for two hours and have nothing to show for it!:damn::damn::damn::rotfl:

Anxiously awaiting the new targetting tutorial.

[IronPerch]

Wow :D ,

i have also done experiments with this kind of tactic and i have also plans for making a tutorial video. Though i have been waiting for new RFB to be "a platform" used in tuorial before starting the project. I haven't made much videos so i'm not going to say for sure that i'm going to release a tutorial video, but i'll try.

So far i have called my methods "Anti-Dick O'Kane" or something like that, but the basic idea is to get 90 degrees hit from non 90 degrees angle (anything from 90 to 180 degrees) with 100% realism settings, with or without TDC. There is two versions of the method: Moving towards the target and moving in same direction with the target. With the first mentioned you have to do the math more quickly (if you play in realtime while charting) and target has less time to react. The latter gives you time to gather the information needed for making the shot, but if you miss you propably are not going to have second change. So far i have used calculator to do the math, but i quess all can be done also by "rule-of-thumb" kind of methology.

Second method i have tried to implement is "fully optical" method with 100% realism, that means i'm able to get all the information needed (also speed and aob) from periscope view, with a few sights and not just by quessing or by "captains eye". This works (normally) with the close range targets and should be good method for situations that need fast decisions and fast data input. Anyway this method also needs calculator (or brains :88)) and you need to know the length of the target (I hope the new RFB has this info in recognition manual ?). There is a pdf-manual for doing this done by Hitman in this forum.

The third issue i have planned to cover is "Charting after first contact" (again with 100% realism) type of method. That should dig into charting and navigating before you are able to get deacent range readings from your target, but you know that there is something in certaing bearing...

Big plans, High hopes... I hope i'll find time and inspiration to make the tutorials.

[Rockin Robbins]

IronPerch, once (not if--you can do it, mon!:up:) you get those movies made, please post them in the [REL] Video Tutorals: TDC + PK advanced thread as well as here. Then it will be time to make a new updated links post over there with my new tutorials, yours and Tale's multi-targeting. FINALLY we're building some tactics momentum.

When these movies are posted, remember the goal is to make these attacks possible. If anybody tries these and has difficulty, please post so we can improve our movies. My guiding principle has always been that it should be so easy my cat can do it, but I realize not everybody has a cat. So we're dependent on everyone who tries our videos out to make suggestions for improvement.

IronPerch, yours will be more technical than mine tend to be. Maybe my cat wouldn't be a good test subject. Where my goal is to make manual targeting so simple that the new guy who's terrified to check that manual targeting box will give it a try, yours is different, but just as important.

Actually, in my tutorial I'm going to use an S-Boat with the stock game complete with silhouettes and velocity vectors to make everything crystal clear. My S-Boat has radar, but without radar, my inital determination of course and speed would be cheating. I'd still do it the same way because my aim is to get beginners to try manual targeting and be successful at it. They can get restrictive on how they gather information later.

[Hitman]

Personally I think that this method has an important problem, and that's that the added torpedo and target speed make it easier to miss. The target is already small, and with a 45º AOB at the moment of impact it presents only 70% of his side to be hit by the torpedo, with the added problem of the increased speed of approach.

90º is still the method with best chances of success :up:

[Rockin Robbins]

Well, Hitman, 16 of 16 torpedoes, 4 of them from 3000 yards say this is plenty accurate. (Of course they're not around any more to testify.) I'll have to shoot four more this evening, at least, while I continue my ground-breaking research into how to screw up a Hypercam movie. Tip #1: leave a Hypercam dialog box open. Then you can pause the recording but it won't resume! Result--half the movie was never taken. http://i196.photobucket.com/albums/aa293/RockinRobbins13/smileys/argggggg.gif I'm going to make these long range shots with Mark 10 torpedoes from a sugar boat for maximum disadvantage. So far I'm finding that the slower angular speed of the target tends to compensate for the inherent advantages of the Dick O'Kane technique. Another thing to think about is that your percentage of duds will be much lower than with a right angle scheme like Dick O'Kane.

Also let's pretend you do miss, Mr Deadeye!:up: You're way out in front and have lots of time to pick up the spare with a Dick O'Kane. If you miss a 20 knot target with a right angle approach, you can just wave goodbye. They're gone. Having a second chance makes this a tactic well worth investigating.

Of course, I'm not just bragging. I'm putting this out there with complete instructions so you can perform it as well as I can and decide for yourself. Let's say it turns out to be 70% as effective as Dick O'Kane. A .700 ballplayer is pretty well paid I think. Oh. There aren't any that good?:huh:

[Nisgeis]

Personally I think that this method has an important problem, and that's that the added torpedo and target speed make it easier to miss. The target is already small, and with a 45º AOB at the moment of impact it presents only 70% of his side to be hit by the torpedo, with the added problem of the increased speed of approach.

90º is still the method with best chances of success :up:

With rounded sterns it actually works out to be about 75% of the target length for a stationary target. The increased closing speed means that the run length is shorter for any given range, therefore the angular length of the target is dependant on the speed of the target and the torpedo. For some targets the angular length is larger. For any given range, the run length is shorter, so errors in your solutions consequently are less important at that shorter run length. Increased closing speed is always a benefit.

EDIT: Also, the target is not moving at the same speed accross the path of the torpedo, for example, a 20 knot target will be moving across the torpedo's path at 14 knots, whereas with a 90 degree attack it going at 20 knots relative to the torpedo's path. So what you lose in length, you gain in slowing the target down. If you imagine a target coming straight towards you, it's bearing doesn't change and it's effective speed accross the torpedo track is 0 knots.

Also, if you are using the PK and attack at 45 degrees, with a divergant spread from aft to stern, the torpedoes all arrive at the same time and explode together - giving no time to evade as in a normal divergant spread from 90 degrees. If your target turns away, he is increasing his apparent target length, making you more likely to hit.

Post war analysis of U.S. torpedo attacks showed that attacks from in front of the target heading in had the highest hit rate, followed by ones at 90 degrees, followed by ones fired from behind the target. historically it's the most successful tactic.

The benefits increase as the speed of the target you are attacking increases and also the benefits increase with slower torpedoes, due to the percentage increase in closing speed.

[doulos05]

Also, if you are using the PK and attack at 45 degrees, with a divergant spread from aft to stern, the torpedoes all arrive at the same time and explode together - giving no time to evade as in a normal divergant spread from 90 degrees.

Just to clarify: You mean bow to stern, correct? Since aft to stern would mean the same thing, or am I confusing my maritime terminology. I don't ask to be smart, I ask because I want to make sure I understand what you're saying.

[Rockin Robbins]

No, he means shoot at the stern first, then middle of target (MOT), and last the bow of the target. This yields the most divergent spread, with the three torpedoes taking the most widely separated paths. Since you are firing the most distant shot first and since the target is moving toward you reducing the distance subsequently fired shots need to travel, all three shots will arrive almost simultaneously. Can you say BOOM?

Once I conquer my incredible ham handedness with Hypercam and make a successful tutorial for the base technique, I'll try one of the divergent spread. It should be semi-amazing.

[Nisgeis]

Also, if you are using the PK and attack at 45 degrees, with a divergant spread from aft to stern, the torpedoes all arrive at the same time and explode together - giving no time to evade as in a normal divergant spread from 90 degrees.
Just to clarify: You mean bow to stern, correct? Since aft to stern would mean the same thing, or am I confusing my maritime terminology. I don't ask to be smart, I ask because I want to make sure I understand what you're saying.
You're absolutely right, I didn't mean to put aft to stern, that would be silly :88). I wrote it just as I was getting ready to leave for work, so... I didn't proof read it properly. Aft to forward I was going to say, but then I decided on stern to bow, but ended up typing aft to stern. But yes what I mean is one in the stern, one at MOT and one at the bow. Thanks for pointing that out.

[doulos05]

Also, if you are using the PK and attack at 45 degrees, with a divergant spread from aft to stern, the torpedoes all arrive at the same time and explode together - giving no time to evade as in a normal divergant spread from 90 degrees.
Just to clarify: You mean bow to stern, correct? Since aft to stern would mean the same thing, or am I confusing my maritime terminology. I don't ask to be smart, I ask because I want to make sure I understand what you're saying.
You're absolutely right, I didn't mean to put aft to stern, that would be silly :88). I wrote it just as I was getting ready to leave for work, so... I didn't proof read it properly. Aft to forward I was going to say, but then I decided on stern to bow, but ended up typing aft to stern. But yes what I mean is one in the stern, one at MOT and one at the bow. Thanks for pointing that out.

Just wanted to make sure I understood what was going on!

[IronPerch]

IronPerch, once (not if--you can do it, mon!:up:) you get those movies made, please post them in the [REL] Video Tutorals: TDC + PK advanced thread as well as here. Then it will be time to make a new updated links post over there with my new tutorials, yours and Tale's multi-targeting. FINALLY we're building some tactics momentum.

Ok, thanks for encouraging i'm optimistic person (most of the time) and i know i can do it if i want :yep:. The thing is that i have also the wife (people seem to mention that time to time in this forum... now it's my turn) + couple of young kids, so normally when i have time to do something by my own the hours are allready a bit late (...yawn). But i'll give a try...

I agree with the "collected tactics" issue. How about a new thread that summarizes all the tactical threads in this forum to the first post of the thread (e.g. "Mobius22 Mods Link Thread!" kind of approach)?




When these movies are posted, remember the goal is to make these attacks possible. If anybody tries these and has difficulty, please post so we can improve our movies. My guiding principle has always been that it should be so easy my cat can do it, but I realize not everybody has a cat. So we're dependent on everyone who tries our videos out to make suggestions for improvement.

Trust me i have had couple of cats and it's a damn sure that those cunning beasts don't want to learn/do anything, if they don't find any bennefit from it to themselves :damn: ... anyway got the point.



IronPerch, yours will be more technical than mine tend to be. Maybe my cat wouldn't be a good test subject. Where my goal is to make manual targeting so simple that the new guy who's terrified to check that manual targeting box will give it a try, yours is different, but just as important.

Actually, in my tutorial I'm going to use an S-Boat with the stock game complete with silhouettes and velocity vectors to make everything crystal clear. My S-Boat has radar, but without radar, my inital determination of course and speed would be cheating. I'd still do it the same way because my aim is to get beginners to try manual targeting and be successful at it. They can get restrictive on how they gather information later.

Well, maybe not so technical as it sounds(?). It's a game not a math lesson :know: . If possible i'll try to mix theory and practice so it's easier to understand why things are how they are. Also i think the basic things for checking the manual targeting box off are pretty well available and explained in this forum, but checking the no map contact updates box is not so well covered. After that the game changes a lot and making a successfull approach, data collection and hitting the target is VEEERYYY satisfying :rock: though it happens not so often anymore (...somebody could make a wife related joke from the last one :D ?)

Btw, I have naturally seen your tutorials while learning the game, so thanks for those!!

[Rockin Robbins]

Let me talk to the moderators and see if there's something we can work out. If we could start a new stickied thread and move some of the posts from WernerSobe's thread to the new one, we could make a great tactics and targeting thread. My point in building on Werner's was that he posted the first three movies, which were really all we had for a year. I started building on his work as he was losing interest, but it seemed logical to build on the stickied thread so I obtained his permission to post the original Dick O'Kane technique tutorial.

There is one moderator who still doesn't fantasize about gory ways of killing my sorry posterior, and I'll apply heavy persuasion.http://i196.photobucket.com/albums/aa293/RockinRobbins13/smileys/pokeeye.gif

[Hitman]

That sounds really good, but I guess you need very accurate target data to make it that reliable :hmm: With good target data -speed, course- any shot is deadly accurate.

Of course I will try it with great pleasure when your instructions are ready :up: My mind is entirely open to any improved form of sinking ships :D

[Nisgeis]

That sounds really good, but I guess you need very accurate target data to make it that reliable :hmm: With good target data -speed, course- any shot is deadly accurate.

That's true for any zero gyro angle, low gyro angles introduce a small error with range and large gyro angle shots rely heavily of range being correct.


Of course I will try it with great pleasure when your instructions are ready :up: My mind is entirely open to any improved form of sinking ships :D
I'll give you some figures, for a target that is for example 600 feet long, firing at a range of 3,000 yards for two set ups, a 45 degree torpedo track angle with zero gyro angle orders and a 90 degree torpedo track angle, with a zero degree gyro angle order. You aren't sure of the target's speed, you think it's about 12 knots, but you know the course. you would fire when the target got to the following bearing:

10 kts 12 kts 14 kts
90 degree firing bearing: 17.9 21.2 24.3
45 degree firing bearing: 10.5 12.1 13.6

As you can see, the difference is firing bearing is much smaller for the 45 degree attacks. The angular length of the target for a 90 degree attack is about four degrees and for a 45 degree attack, it's a bit above three degrees. So, you've lost less than a degree in angular length and your firing bearings are closer, reducing the impact errors in speed estimates.

The Dick O'Kane method is very tolerant of course errors, but very harsh on speed estimates. This new method is tolerant of speed and course errors.

[Xia288]

Can't wait to use the new attack method !!! Dick O'Kane works great for me. So let me get this right before I try this new way tonight:

1. Aim target at 45 degree
2. with fast top setting aim target at +10 degree when target is in the cross.
3. Aim & fire aft first, MOT 2nd and bow last.

wait for the BOOM !

If missed, go back to 2nd chance with 90 degree Dick O'Kane way.

Correct ? Gents.

Xia288:-?

[Rockin Robbins]

Uploading video now. Would you believe a successful daylight surface attack for the first John P Cromwell tutorial video? In a really great thunderstorm? I had to close to 1800 yards to see him at all and shot with the TBT. Although I say in the tutorial that I though I only hit two before the mission ended with target destroyed, on the audio you can clearly hear 4 impacts. In the video you can't see crap in the TBT.:rotfl:

I show how to do a vector analysis, where you can pick the torpedo track angle to the target (45º for the John P Cromwell attack) and draw a scale diagram to find the proper lead angle to aim the periscope.

Then I show how to set up the attack in the TDC by rule of thumb that make the attack very simple to figure in your head without any outside tools whatever.

In the process I explain what the S in S-Boat means, demonstrate how to drive like a drunken sailor and other semi-entertaining behaviors meant to demonstrate that I have no business making tutorial movies of anything. I still have to work on sound levels. 3/4 of the way through the movie the sound comes unsynchronized from the video by about 5 seconds.

Too bad! I've never seen a surfaced daytime attack done before and it stays! We'll make other, clearer movies later. I'm just glad to get this one out of here. I thought I was cursed there for awhile and just want to get away from movie making for a few days.

One hour and six minutes till showtime!:|\\

[Rockin Robbins]

Sorry about the delay. Here is the video for the basic longitudinal spread. Edit: now a much smaller 7zip file!
John P Cromwell attack technique (http://files.filefront.com/John+P+Cromwell+Tutorial7z/;12127008;/fileinfo.htmlhttp://files.filefront.com/John+P+Cromwell+Tutorial7z/;12127008;/fileinfo.html)

See the description in my last post. This one is strictly shooting Dick O'Kane style: longitudinal spread (all torpedoes take the same path to the target and are distributed from target's bow to stern by timing alone). Coincidentally, because it wasn't planned that way, this is also the first video ever released of a successful daylight surface attack. I'll replace the above AVI with a 7zip later. Enjoy! Please ignore the loss of sound synchronization in the last part of the video. I was cursed from the moment Hitman said, "this probably isn't a good idea." http://i196.photobucket.com/albums/aa293/RockinRobbins13/smileys/whydidntIthink.gif

OK, written instructions on how to execute this thing, written purely from memory, so don't shoot me:

With radar, plot two positions of the target 3 minutes apart onto the nav map. The distance between the two positions in hundreds of yards is the speed of the target, 600 yards equals 6 knots. Enter the speed into the TDC.

On the nav map with the ruler, draw a line from the first position, through the target and extending past your submarine. Measuring with the compass rose obtained with tool help on you can determine the target's course.

If this reveals that you can take a 45º approach angle to the track from ahead of the target, it's time to execute a John P Cromwell attack. Estimate the intercept point for a 45º approach. It doesn't matter if the estimate is wrong. With the protractor, click on the track further out from that point, then back toward the target at that estimated intercept point and lastly right beside your boat. Read the angle. It won't say 45º. Grab the vertex (the angle itself--the middle click point) and move it up or down the course until it says 45º.

Now turn your boat parallel with that line. If you have the 360º bearing plotter (hope you have the 3000 yd/meter variety!) this is a trivial task. If you don't, read the course off the protractor line with the ruler or protractor compass rose.

Pick your periscope aiming bearing. For a target coming from left to right, I'd pick 350º for fast Mark 14, Mark 23 or Mark 10, 345º for slow Mark 14 or Mark 18.

Now you have to calculate the angle on the bow (AoB). This is easy, don't leave now! The AoB equals 45º minus your lead angle. If your shoot bearing is 350º, you are 10º from the zero bearing. So 10º is your lead angle. 45º minus 10º equals an AoB of 35º. Now which side of the target are you looking at? In the video it is the starboard side, so the angle on the bow is 35º starboard.

For the other lead angle, our shoot bearing is 345º. That is 15º from the zero (360º) bearing. 45 minus 15 equals an AoB of 30º port or starboard, depending on whether the target is coming from the left or right. For whether the AoB is port or starboard, answer the question "what side of the target am I looking at?" There's your answer.

Range doesn't matter but bearing does. Point your aiming device, usually periscope, up the shoot bearing you've selected and press the send range/bearing to TDC button. You are ready to shoot.

Now it's a matter of remaining undetected and with the periscope pointed at the shoot bearing, send torpedoes as juicy parts of the target pass the crosshairs.

Watch the destruction!

Nisgeis will be by later with complete instructions on how to do the vector analysis, which will give you the periscope bearing for an attack giving you a perfect zero gyro shot every single time! Don't be afraid kiddies, a little math never hurt anybody. This is analytical geometery and very impressive to beautiful girls at the bar while you're in port! Demonstrate this on a napkin and they're YOURS!!!! Pay attention.

[Nisgeis]

Robbins, you should try compressing it with DivX or XVid, it will give a compressed video and the quality will still be very good. I couldn't see the target in the TBT at all in the video. Nice explanation though!

You might find it easier to get the right course by using the navigation plotter waypoint and just dragging it so it's parallel, it's a lot easier than matching a course by hand.

[matelot2001]

RR, Nisgeis and anyone else who I have failed to mention...

Thank you for your time and effort in finding yet another method for sinking the enemy.

I'm in the process of downloading your video, RR (comments to follow, if require!! ;)), and will try the John P Cromwell method after watching it.

Once again - Thanks for the time and effort you all put into our community.

Yours Aye

[Kruger]

I tried this attack technique last night, from 3500 yards, thus being able to use the high speed torpedo setting and also not being very close to the escorts. It works like a marvel :yep:.

10 torpedoes, 5 kills (each ship was attacked by 2 torpedoes, one set to minimal depth, one to keel depth, the former set to impact and the latter to magnetic).

One large freighter was stubborn enough not to sink, but his engines were a wreck, so late in the night I was able to surface and finish him with the deck gun. :arrgh!:

[Nisgeis]

The formula for finding the correct bearing to fire on is too complicated to do on the fly without using a calculator and a rule of thumb just isn't accurate enough. To get round this, the easiest way to get the correctr bearing is to draw the problem on the navigation map. With your protractor, draw a straight line across, then put your second point and then make an angle equal to the intersection angle of your target's course. For the first example bewlo, that would be 135 degrees.

The basics of it are, to work out where an object will be prior to a collision. You can work out where two objects are when they collide easily enough - as they are at the same point. To work out where they would be, you just need to draw their paths back from where they came from. So, in the first example below, draw your 135 degree line, then from the centre of the angle draw out along the horizontal to a range equaling the speed * 100, which will give the range travelled in three minutes. The range is irrelevant, we're just making it a multiple of 100 so that there is enough accuracy in the ruler tool and you don't have to guess where the right point is. For the example below, you'd draw a line 1,200 yards long. Then down the other leg of the angle, draw a line equal to your torpedo's speed * 100. This will give the equivalent distance travelled by the torpedo when the target has travelled its speed * 100. Let's say you are using a Mk. 14 on fast, which travels at 46 knots.

The scale of *100 yards is only relevant to get enough accuracy on what range you are drawing. You could if you wanted to draw speed * 1 mile, to give 12 miles for your target and 46 miles in the same time, or 12 feet and 46 feet, or 12 millimeters, but there's not enough range resolution for less than hundreds of yards. Feel free to plot in *1 km, or *100m whichever you are using - as it's a constant bearing problem, the range scale doesn't matter, only the angle matters.

The drawing you have just made shows were the target and torpedo will be in relation to each other for any scale. Not all you have to do is to measure the angle between where the target is at the start and where the collision point is. So, with another protractor tool, click on the target start point, click on the collision point then finally click on the torpedo start point. This will give you the lead angle to fire at for a zero gyro angle shot.

http://i251.photobucket.com/albums/gg307/Nisgeis/John%20P%20Cromwell/45DegreeAttack.jpg

Example 1, Diagram for a 12 knot target and a 46 knot torpedo shot for a torpedo track angle of 45 degrees.

You can also use this for any other angle you like:

http://i251.photobucket.com/albums/gg307/Nisgeis/John%20P%20Cromwell/60DegreeAttack.jpg

Example 2, Diagram for a 12 knot target and a 46 knot torpedo shot for a torpedo track angle of 60 degrees.

http://i251.photobucket.com/albums/gg307/Nisgeis/John%20P%20Cromwell/90DegreeAttack.jpg

Example 1, Diagram for a 12 knot target and a 46 knot torpedo shot for a torpedo track angle of 90 degrees.

I hope that's clear, but perhaps not. Any questions?

[matelot2001]

Robbins,

As Nisgeis said - Nice explanation (as always) but that time lag with the sound and invisible target kinda puts a dampener on things.

But, who am I to comment - I wouldn't know how to produce a video. Hell, I can't even put my signature on a website so I can URL it's location. Too long at sea playing with RADAR blips, not enough time behind a PC learning fundamentals!!

Now I have to get my head around the editor to produce a practice mission to test the John P Cromwell method - "Gentlemen, I may be gone some time!!"

Yours Aye

[Rockin Robbins]

Pick and choose. I choose both methods! There is plenty of time. Actually if you guess the wrong lead angle your gyro angle would be less than 5º off with a pretty terrible guess. That won't impact the accuracy of your shot.

We fuss and pick when we're making these tutorials, anticipating that equally fussy people will say, "You did this wrong! Your shoot bearing should have been 349º, not 350! You idiot!" Actually a torpedo with a 1º gyro angle is functionally as accurate as one with a zero gyro angle. So is one with a 5º or a 10º gyro angle. You'll NEVER be 10º off using a rule of thumb.

Rules of thumb allow you to be just as accurate as the guy with the vector analysis who sends his torpedo straight up the zero line, but with rules of thumb you don't have to remember how fast that Mark 10 is, or make the mistake of selecting slow speed for your Mark 14 and drawing the vector analysis for fast speed. You can verify the bearing of the torpedo track on the attack map.

In shooting, some things can be close enough, and others need to be accurate. In the John P Cromwell attack, speed measurement is more forgiving than the Dick O'Kane attack, but the AoB measurement is more critical. Fortunately, in both types of attack our AoB can be 100% accurate and calculated in your head in less than a second. There is no guesswork there, just a simple to remember rule.

In the Dick O'Kane attack you are attacking 90º from the target track. The AoB is 90º minus the difference of your shoot bearing from zero. A shot sighted up the 350º bearing line is ten degrees from zero (360). It has an AoB of 90º minus 10º equals 80º port or starboard, depending on which side of the target you are looking at.

In John P. Cromwell you are attacking 45º from the target track. The AoB is 45º minus the lead angle you select. A shot sighted up the 350º bearing line has an AoB of 45º minus the 10º lead angle equals AoB 35º starboard or port, depending on which side of the target you are looking at.

These rules are neither difficult to calculate without a calculator, nor difficult to remember. They are exact results, not approximations.

But both methods are prone to error. The vector analysis method is prone to the error of setting wrong torpedo speeds, or misremembering the torpedo speed. This error will result in a miss.

The TDC/rules of thumb method is prone to an error of getting the gyro angle a couple of degrees from zero. This results in a sunk target and no knowledge of the error at all unless you investigate the results later or check the attack screen before you shoot.

I'll take the error that sinks the target! Your results may differ.

And there's plenty of time to do both! The video shows you how to do the vector analysis right on your nav map without pencil and paper. Use both and you check the possible errors of both methods with the strength of the other. That's the policy I recommend. These are complimentary, not competitive methods.:up:

[Rockin Robbins]

You might find it easier to get the right course by using the navigation plotter waypoint and just dragging it so it's parallel, it's a lot easier than matching a course by hand.

Hell, that's no fun! It's much more fun and entertaining to drive the boat like a drunken sailor! It only took me three tries to get on course...:rotfl::88) The admiral made me put a Student Driver magnetic sign on my fantail.

[Dennus]

When I first read about teh Dich O'Kane method, I thought "this is about the relation between the speed of the target vessel and the speed of your torpedo".

Yet in Rockin Robbins guide I only found two shooting bearings 10 deg for fast and 20 deg for slow torpedoes.

So I set out calculation my own shooting bearings at target vessel speeds using the following formula:

tan(a)=Vtarget/Vtorpedo

a = invtan Vtarget/Vtorpedo

where a = angle and V = speed

So I came up with a nice table with shootingbearings for speeds from 1 to 20 knots for slow and fast torpedoes.

As it turned out my whole table was a waste of time. You know why?

Because your so damn close (> 1100 yards) that rough estimates like 10 deg for fast and 20 deg for slow torpedoes do the trick.

Since the Cromwell attack is based on the same principle i.e. the relation between target speed and torpedo speed, you don't have to worry about precise schooting bearings if you take care that your in a well let's say 1500 yrd radius from your target.

I use the Dick O'Kane method frequently and it works like a charm. It also gave me insight in how to figure out the AOB, which led me to use the Position Keeper.

The PK is my friend now and I seldom miss. The only thing that I have trouble with is shooting two convoy targets at a time with the PK. I saw a videoguide for it once, but I can't find it anymore. Do any of you guys have some advice on this for me?

[Rockin Robbins]

The guy who has the best instructions on this is tale. Tale's instructions could work as well for Dick O'Kane or John P Cromwell too! He's got a great movie.

[XLjedi]

You can call it Cromwell or whatever you like I s'pose.

However, you should be able to use the TDC component of the PK to get the firing solution without having to draw things on the map. I know you dispatched with all that in your simplified DO'K method.... but there was a time when I mentioned that you should use the TDC component of the PK to calculate the intercept angle for you.

My initial recommendation to mimic Fast-90 was to use the TDC to setup a firing solution (close to a zero gyro angle) without having the PK continue to track the target.

http://www.subsim.com/radioroom/showpost.php?p=627351&postcount=134

I believe my exact same suggestion can be followed in this case only instead of a 20° bearing with a 70° AoB, it's 20° bearing and 35.5° AoB (or just 36°)

You're not really describing anything different here... you just forgot (or never bothered to use) the TDC to setup the firing solution as I originally suggested.

The nod to O'Kane was merely acknowledging his recording of the tactic, that both he and Morton used, which involved overriding the PK tracking and firing as points of interest passed the wire. Same thing here...

Calling it Fast-90 was deemed inappropriate because the US Fleetboat optics didn't allow for pan-and-fire solutions (which was at the heart of Fast-90).

But... I don't have any objections to you guys calling a 45° approach whatever you like. :ping:

It's all good... :up:

[Rockin Robbins]

There are a couple of reasons I included the vector analysis in the tutorial movie:

1. I love elegant solutions that can be verified by inspection. Vector analysis is fun, even for normally math-challenged people.

2. Respect for Nisgeis, who suggested this tactic to begin with and didn't understand my explanation of the Dick O'Kane attack. I thought "What if there are more like him who are having problems with the TDC method but could use the vector analysis method?" They deserve help too.

3. Although I believe the TDC method is less prone to error than the vector analysis method, it is true that one method can be used to verify the other.

4. While you are in port, you go to the local watering hole. Inside is this gorgeous piece of womanflesh. You approach her and find out she's some kind of philologist or something and you can't seem to make any kind of connection. You merely whip out a napkin and draw the vector analysis of your last torpedo attack. SHE'S YOURS PAL!!! Take her home.:rotfl:

Aaronblood, I'm a promoter of ideas. Some of them are irrelevent, such as what the "s" in S-Boat stands for. Some, such as the vector analysis, may be good only for understanding the underlying concept behind the attack. The vector analysis can also be used to show why in this type of solution the range doesn't matter. What happens to the angles when you double all the measurements? (they remain the same). And vector analysis is just plain fun. Yeah, I'm crazy as you are!:up:

[XLjedi]

Vector math can be fun...

If only things had exploded when I got answers right in HS Algebra; would've made that class far more interesting. :yep:

I kinda like using the TDC that's supplied in the game. Although I have my doubts about the historical accuracty of the in-game distance knob that disallows full manual input! Thankfully if we're working with close to zero-gyro shots, it doesn't really matter.

[Rockin Robbins]

I agree. Vector math is fun if there's a boom at the end, but a mechanical computer is even more fun and it helps eliminate some errors that are easy to make in the vector chart. Now if I can figure out how the thing does e-mail...

Oh, there is a mod that allows for direct range input to the TDC. I'll dig it up.

[Nisgeis]

You can call it Cromwell or whatever you like I s'pose.

However, you should be able to use the TDC component of the PK to get the firing solution without having to draw things on the map. I know you dispatched with all that in your simplified DO'K method.... but there was a time when I mentioned that you should use the TDC component of the PK to calculate the intercept angle for you.


I asked earlier how your method is meant to work, but I didn't get an answer, the link you give doesn't show enough of the previous discussion for me to understand it. Do you put in 7 knots regardless of the target speed, or the target speed? Could you please give a brief explanation of using the TDC to get the firing bearing for a zero gyro angle shot?


My initial recommendation to mimic Fast-90 was to use the TDC to setup a firing solution (close to a zero gyro angle) without having the PK continue to track the target.

http://www.subsim.com/radioroom/showpost.php?p=627351&postcount=134

I believe my exact same suggestion can be followed in this case only instead of a 20° bearing with a 70° AoB, it's 20° bearing and 35.5° AoB (or just 36°)


I tried that and it doesn't work. It missed by miles. Where are you getting 35.5 degrees from?


You're not really describing anything different here... you just forgot (or never bothered to use) the TDC to setup the firing solution as I originally suggested.

The nod to O'Kane was merely acknowledging his recording of the tactic, that both he and Morton used, which involved overriding the PK tracking and firing as points of interest passed the wire. Same thing here...


That's not quite right. The method O'Kane used, by holding the bearing on the TDC is not the same as turning the PK off.

I didn't forget to use the TDC... It's also not a case of not bothering with the TDC. If I could use the TDC to find an accurate firing bearing for a zero gyro angle in a simple way, without having to re-enter information, then I would use it. My aim is only to get a firing bearing for a zero gyro angle shot so that range is not important. I also wanted to get an exact 45 degree torpedo track angle. If you can show me a way to get that from the TDC, I'd probably use it. It's only a couple of lines, it's not like you have to complete a 3d sketch of the ship you are shooting at.

Yes, you can get an innacurate solution whose innacurasy doesn't matter because you are shooting from 800 yards, but if you are shooting from 800 yards, you might as well just shoot with a lead angle of speed + 3 degrees with zero gyro angles.

[Fincuan]

Could you please give a brief explanation of using the TDC to get the firing bearing for a zero gyro angle shot?


I know you didn't ask me, but here's one way to do it(using the 45 degree attack). I'm assuming that by this point you know the target's course and speed and are pointed at a 45-degree angle to the target's predicted track.


Set up your torpedoes. Changing torpedo speed will naturally ruin the calculations.
Point scope to zero bearing, set distance to for example 1500 meters and send to TDC
Set AOB to 45 and speed to whatever it is and send to tdc
Note the gyro angle. Let's say in our example it's 352 degrees, so the difference to a zero angle shot would be 8 degrees.
Calculate a zero-degree firing bearing by adding or substracting the above difference depending on the AOB(port or starboard). Calculate a new AOB for that bearing by substracting the above difference from the previous AOB of 45 degrees.
Move scope to the new firing bearing and mark. Set the new AOB and send it to TDC.
Wait for the target to pass the crosshairs and fire


I have one huge problem with the 45-degree attack: In SH4 ships usually turn towards the torpedoes when they see them. In a 45-degree zero-gyro angle attack the torpedo track angle is already 45-degrees, and when the ship turns into the torpedo the the angle is even less resulting in plenty of duds. You can counter this to some extent by using fast speed in the torpedoes, but you all know how reliable the early war ones are with that setting...

[Munchausen]

Or, after setting the target's AOB (45 degrees left/right +/- lead), go to the attack map and take a look at the torpedo track line (green). If your sub is already oriented like you've planned (for a 45 degree attack), the green line will tell you if you're set up for a zero-degree shot.

If not, eyeball the change, adjust your AOB and crosshairs accordingly, and send a new bearing to the TDC. Otherwise, leave your crosshairs where they are and shoot as the "juicy parts" of your target sail into your crosshairs.


Edit: One way to make manual range changes to the TDC (based on a thread I can't find anymore).

1.5 \Data\Menu\cfg\Dials.cfg: made changes so that manual input on the range meter could be increased to max range.

[Dial58]
Enabled: “RelativeDrag=Yes” to steady the index marker (to keep from “chasing the dial.”)

[Dial59]
Enabled: “Cmd=Set_tgt_sel_value;”
Enabled: “CmdOnDrag=Yes”
Enabled: “RelativeDrag=Yes” to keep wheel from spinning when attempting to dial a range.

[Nisgeis]

Set up your torpedoes. Changing torpedo speed will naturally ruin the calculations.
Point scope to zero bearing, set distance to for example 1500 meters and send to TDC
Set AOB to 45 and speed to whatever it is and send to tdc
Note the gyro angle. Let's say in our example it's 352 degrees, so the difference to a zero angle shot would be 8 degrees.
Calculate a zero-degree firing bearing by adding or substracting the above difference depending on the AOB(port or starboard). Calculate a new AOB for that bearing by substracting the above difference from the previous AOB of 45 degrees.
Move scope to the new firing bearing and mark. Set the new AOB and send it to TDC.
Wait for the target to pass the crosshairs and fire

I know of that method, I tried to refine it before coming up with the vector analysis solution. What I am looking for is a way for the TDC to give you the firing bearing for a zero gyro angle shot without having to re-enter information. Using it way way, you have to re-enter the AoB and feedback the previous error into the solution and you have to do it about three times to get it accurate. I think it's not as easy as just drawing some lines. I know how to use the TDC and use it in automatic mode, but my aim for this method was to get a method that gives you the right solution all the time, as opposed to the right solution, if you happen to guess the correct firing bearing.

Some people are more visual in their problem solving and may find drawing a solution much more intuitive than someone who is more word orientated.

I think for people that want to get into manual targetting, but are a bit worried about the TDC, the simpler the better. This is after all, who this method is for. It works not only for 45 degree attacks, but for 90 degree attacks, 60 degree attacks, even attacks from behind and will give the right solution every time, so people may well see their hit rates increasing with these zero gyro angle shots. The simpler the better if you ask me. Unless that simplicity gives you wrong solutions of course :up:.

[Fincuan]

I figured by your posts you'd know a thing or two about TDC :)

I forgot to add to that explanation that it doesn't give a gyro angle of exactly zero degrees without trial and error, but close. Your precision won't suffer becuase the TDC is still used to calculate the new gyro angle. I tried the drawing method and it is definitely faster and more precise if you want the gyro angle to be exactly zero degrees.

Imho still the best way of them all, even though it has nothing to do with this thread, is using the PK :up: By the time the target gets into a firing position you'll have verified the solution so many times there should be little error left. Firing spreads is easy without having to keep the scope up for aiming, and you can also maneuver the boat around and fire at any time without having to recalculate anything. Gyro angle and torpedo track angle will also be constantly available and useable in deciding the best moment to fire.

[Rockin Robbins]

The vector analysis, even if it were completely useless is an indispensable tool because it teaches you why the attack works. It gives you confidence in your method. Confident people make fewer mistakes because they remember the steps and their purpose while they go through the procedure. It helps to be able to visualize what is really going on.

Fortunately vector analysis is also so useful that you could do the whole attack if the TDC were thrown overboard. Overboard, if you haven't guessed, would be a nice place for the TDC in Nisgeis' sub. He has a unique and very productive outlook on how to shoot a torpedo. He has no need but idle curiosity to know anything about the TDC.

@Fincuan, the problem with the PK is that it needs a range. Our attack methods work so well at extreme ranges simply because range cancels out of the equation and becomes irrelevant as long as the torpedo can run long enough to get there. We, for the most part, are unwilling to cheat by manually inputting a range to the TDC based on a visual sighting to match the pip on the nav map. I personally have no problem at all doing precisely that with radar.

A future iteration of the John P Cromwell technique will use the PK to do a divergent spread: stern, MOT, bow. This should result in near simultaneous strikes at all three points. If the target does the predictable during clear weather and turns into the attack, he will merely be struck by two instead of three. A longitudinal spread, with torpedoes advancing in a single column is relatively easy to avoid. A divergent spread is not! This spread, by the way, was advocated by Nisgeis in one of our earliest talks for formulating this technique.

Anyone who wants to try this out in the safety of the balmy waters off the coast of California near Catalina Island with nobody around but your target tanker, here you go (http://files.filefront.com/Fleet+Boat+Training+Mission7z/;10079763;/fileinfo.html). Just unzip it into your Wolves of the Pacific\data\single missions directory.

[Munchausen]

It works not only for 45 degree attacks, but for 90 degree attacks, 60 degree attacks, even attacks from behind and will give the right solution every time, so people may well see their hit rates increasing with these zero gyro angle shots.

:hmm: I thought the advantage of the 45-degree attack was that it provided an easily computed collision course ... using a simple ratio between target speed and torpedo speed. How does it work if you're attacking at other angles?

[XLjedi]

Sorry... I cut the 70° in half to 35° I guess I should've cut the 20° in half too.
(and I'm just gonna claim stupidity for saying 35.5° is half of 70°) :oops:

Assuming you're on a 45° track to the target TC and you just set AoB as 35° you should be able to get a +-5° solution (close enough to zero) at the 10° bearing. You would set the target speed for whatever the target speed is and let the TDC calc the +-5 track. Just leave distance at ohhh... 1000-1500 or so and you should be fine.

When I suggested a 20° approximation for the 90° approach angle I was assuming you were going to use your TDC to get an exact track solution (but close enough to zero gyro) to hit anything inside of 2000 yds (maybe further).

I haven't tested it, but I would think that a +-5 gyro angle wouldn't introduce enough error to miss inside of 2000yds. It's only the little bit of torpedo advance that skews the solution with regard to distance, and I doubt a few degrees is gonna matter too much if I just set a 1500yd distance and forget about it.



So you're on a 45° track and target is moving at 12kts.

Try setting aiming wire at 10° and AoB 35°, speed 12 and MARK (hit input button). That should give a solution close to zero gyro. Now fire as points of interest pass the wire on the 10° mark.

I was just looking for ways to simplify the TDC data entry and allow the TDC to solve for the angle... similar to Fast-90. Notice the only variable above is speed, I don't need to keep a lookup table of degrees for zero gyro shots.

But it's up to you all if you want to do the math, if you like super precision and hitting targets at 8000 yards that's fine too. :yep:

10 and 35 seem to work OK for a 46kt torpedo... and what's the other torp speed? ...probably close enough for other speeds too.

[Joe S]

Back in the days of Sub Battle Simulator, I used a manual plot and the following forumula for a firing solution: Range to track, at point of torpedo hit, divided by torpedo speed, equals torpedo run time to target. Run time to target X Target speed = distance travelled by target during torp run. plot the distance travelled by target back along its track from the point of impact and when the target gets to that spot you fire the torpedo It really doesnt matter what the aob is . It seems like this Cromwell method is based on the same idea. Based on my experience with Sub Battle Simulator (we're talking hundreds of hours) , I know it is a good method.My question is, what is the importance of the 45 AOB? I really dont think it makes any difference, except that the smaller the angle the smaller the profile of the target at the point of impact. The video and written instructions are great, good job! Joe S

[Munchausen]

It works not only for 45 degree attacks, but for 90 degree attacks, 60 degree attacks, even attacks from behind and will give the right solution every time, so people may well see their hit rates increasing with these zero gyro angle shots.

:hmm: I thought the advantage of the 45-degree attack was that it provided an easily computed collision course ... using a simple ratio between target speed and torpedo speed. How does it work if you're attacking at other angles?

After thinking about it awhile, I realized this method can be done at any angle, without using the TDC at all ... but (I think) I did it bass-ackwards. Here's what I did, using RR's single mission scenario.

1. Took two fixes of the target, three minutes apart.
http://img.photobucket.com/albums/v97/pjcham/SH4/01_fixing_target.jpg

2. Drew a line through both fixes and extended it past my sub's present position.
http://img.photobucket.com/albums/v97/pjcham/SH4/02_plotting_course.jpg

3. Determined the target's speed ... about 12 knots.
http://img.photobucket.com/albums/v97/pjcham/SH4/03_target_speed.jpg

4. After making a random turn (nothing specific ... just somewhere between 45 and 90 degrees) toward the target's track, checked my heading on the compass ... which happened to be about 273 degrees.
http://img.photobucket.com/albums/v97/pjcham/SH4/04_sub_heading.jpg

5. Plotted my heading (273) on the navigation map.
http://img.photobucket.com/albums/v97/pjcham/SH4/05_plot_heading.jpg

6. Overlaid a "hypothetical" triangular solution where:

The side corresponding to my heading = 4600 yds (torpedo speed x 100).
The side corresponding to the target's heading = 1200 yds (target speed x 100).

After adding the third side of the triangle, the angle opposite the target's side measured 12 degrees.
http://img.photobucket.com/albums/v97/pjcham/SH4/06_basic_trig.jpg
Note: The two "heading" sides are marked off with white goalposts and the angle opposite the target's heading is in red. The 12-degree (lead) angle will work for the (shorter) real distance between target track and sub's position because the ratio between the hypothetical triangle and the actual triangle is the same.

7. Transposed the lead angle (12 degrees) to sub's present position. (This step isn't necessary ... it just makes it easier to judge how close the target is to the firing point.) Note the ratio between the two triangles.
http://img.photobucket.com/albums/v97/pjcham/SH4/07_same_lead.jpg

8. Identified the target.
http://img.photobucket.com/albums/v97/pjcham/SH4/08_ID_target.jpg

9. Set the torps: high speed, contact/influence, 17 feet (and then opened tubes 1, 2, 3 and 5).
http://img.photobucket.com/albums/v97/pjcham/SH4/09_set_torps.jpg

10. Checked the attack map to make sure gyro angle was set to zero.
http://img.photobucket.com/albums/v97/pjcham/SH4/10_confirm_gyro.jpg

11. Turned periscope 12 degrees left (to 348 relative) and fired as the "juicy parts" of the target sailed past the crosshairs.
http://img.photobucket.com/albums/v97/pjcham/SH4/11_ready.jpg

12. Hit ... slightly after of aim point. The last three torps hit just about on target. None missed.
http://img.photobucket.com/albums/v97/pjcham/SH4/12_hit.jpg

So, was that bass-ackwards or what?

[Rockin Robbins]

Bass-ackwards??????? You're dead on! And that makes vector analysis worth knowing. I just started some research. It's really weird news. It really doesn't matter except for curiosity. I'll start another thread for that one.

Suffice it to say that you better be taking zero gyro shots at extreme range or putting a high number in the range for the TDC when you shoot. But it gets worse....

[Nisgeis]

Imho still the best way of them all, even though it has nothing to do with this thread, is using the PK :up: By the time the target gets into a firing position you'll have verified the solution so many times there should be little error left. Firing spreads is easy without having to keep the scope up for aiming, and you can also maneuver the boat around and fire at any time without having to recalculate anything. Gyro angle and torpedo track angle will also be constantly available and useable in deciding the best moment to fire.

I agree, I use the PK without map contacts on and use the PK to verify my target data, very nice and you can also run alongside. This method here is meant as an introduction only, as an intermediate step between auto targetting and using the PK, just to get people's confidence up and increase the enjoyment factor. It's much better sinking a ship without auto targetting, IMHO.

[Nisgeis]

Fortunately vector analysis is also so useful that you could do the whole attack if the TDC were thrown overboard. Overboard, if you haven't guessed, would be a nice place for the TDC in Nisgeis' sub. He has a unique and very productive outlook on how to shoot a torpedo. He has no need but idle curiosity to know anything about the TDC.

I use the TDC exclusively with the PK on and map contacts off. It's extremely powerful and more people should use it, but only when they are happy without auto targetting. This method here is purely an easy method of hitting targets without making use of the TDC, or if you like you can use the TDC to verify your attack. Once you are happy you can attack in manual mode, then it's a smaller step to using the TDC with the PK on.

[Nisgeis]

:hmm: I thought the advantage of the 45-degree attack was that it provided an easily computed collision course ... using a simple ratio between target speed and torpedo speed. How does it work if you're attacking at other angles?

It might be easier to imagine a collision, let's say between two cars. If you know car A was driving at 60 MPH due east towards a crossroads and car B was travelling at 30 MPH due North towards the same crossroads and you know they collided, then you can calculate lots of things. First, because you know the impact point was the crossroads and you know the direction and speed each car was going, you can in effect play time backwards and look at how things were one minute ago. If you start from the crash and rewing time, after one minute Car A will be 1 mile west of the crossroads and Car B will be 1/2 mile South of the crossroads. If you were in Car A, you could look to your right and see Car B, at a bearing of about 26.5 degrees. From Car B, you would see car A to your left at a bearing of 296.5 (63.5 derees to the left). For each minute forwards or backwards, as long as the two cars remain on their straight courses, the angle between the two of them will remain the same, regarldess of how far they have travelled.

If you reversed time back to one hour before the crash, assuming they both travelled at a constant speed on the same course, they would both arrive in one hour's time at the crash. At any given point in time, Car A would be at a bearing of 296.5 from car B and car B would be at a bearing of 26.5. Running time forwards, as they get closer to the crash point, the bearings remain the same, but the range reduces. This is know as a contant bearing, reducing range situation and is a definite sign you will collide.

The above is for a crossroads at 90 degrees, but it doesn't matter what angle the cars are approaching each other from. If you know they will collide, you can work out where they will be before the crash. Even if they were approaching each other head on, the same would be true. Though the bearings would be 0 for each car.

If you take any collision problem, where you know the angle at which two objects will collide, and you know the speeds, then you can work out where they were before the crash. Then you can also work out where one object should be in order to collide with another. If you are in car B and you want to deliberately crash into Car A, and you know that car A is travelling at 30 MPH at a course 90 degrees to you, then you can work out that if you want to hit him travelling at 60 MPH, you would hit car A, if you were approaching the crossroads and Car A was at a bearing of 26.5 degrees. If he was at 10 degreesm he'd pass ahead of you and if he was at 40 degrees, you'd pass in front of him.

It all relies on knowing the angle of intersection and the speeds to work out what point you need to start off to ensure a hit.

[Nisgeis]

Sorry... I cut the 70° in half to 35° I guess I should've cut the 20° in half too.
(and I'm just gonna claim stupidity for saying 35.5° is half of 70°) :oops:

Assuming you're on a 45° track to the target TC and you just set AoB as 35° you should be able to get a +-5° solution (close enough to zero) at the 10° bearing. You would set the target speed for whatever the target speed is and let the TDC calc the +-5 track. Just leave distance at ohhh... 1000-1500 or so and you should be fine.

When I suggested a 20° approximation for the 90° approach angle I was assuming you were going to use your TDC to get an exact track solution (but close enough to zero gyro) to hit anything inside of 2000 yds (maybe further).

I haven't tested it, but I would think that a +-5 gyro angle wouldn't introduce enough error to miss inside of 2000yds. It's only the little bit of torpedo advance that skews the solution with regard to distance, and I doubt a few degrees is gonna matter too much if I just set a 1500yd distance and forget about it.


Right, I see what you mean, that works great for ranges of about 1,500 yards as you say. It's a great method for close in attack, nice and easy and should give you results. Certain factors come into play when you are using it for longer ranges though and that's what this method is for - just an all round method that works. Some may not like drawing a little diagram, others may prefer it. I prefer to use the TDC in full PK mode, but each to our own.


So you're on a 45° track and target is moving at 12kts.

Try setting aiming wire at 10° and AoB 35°, speed 12 and MARK (hit input button). That should give a solution close to zero gyro. Now fire as points of interest pass the wire on the 10° mark.

I was just looking for ways to simplify the TDC data entry and allow the TDC to solve for the angle... similar to Fast-90. Notice the only variable above is speed, I don't need to keep a lookup table of degrees for zero gyro shots.

But it's up to you all if you want to do the math, if you like super precision and hitting targets at 8000 yards that's fine too. :yep:

10 and 35 seem to work OK for a 46kt torpedo... and what's the other torp speed? ...probably close enough for other speeds too.

That makes more sense, thanks for clarifying. It does work for close in ranges of around 2,000 and under. The other torpedo speed for the mk.14 is 31 kts. The mk.18 is 29 kts :o and the Mk.10 is 36 kts.

The Dick O'Kane method works for close in targets, but has certain things removed from the target problem that become apparent when shooting at longer ranges. The first is that you need to put a range into the TDC and for most bearings, this means a small gyro angle. A large gyro angle, as we know needs very precise range data to score a hit and setting a solution for 1,500 yards for a target 4,500 yards away will mean a significant range error. The gyro angle is further exagertaed, as the reach on a mk. 14 is 200 or so yards, so for a target 1,500 yards away, the gyro angle is calculated for a run of 1,300 yards. This increases the gyro angle and increases the error set for the gyro angle. For such range errors, even a small gyro angle will result in a miss at longer ranges.

The second problem the static PK has is the AoB of the target and rnage aren't adjusted, as you close on the target's track, the AoB will also change and that not being updated adds a small error into the gyro angle already calculated. This effect is reduced if coming on for a slow creeping submerged attack, but is noticable with a high speed surface attack. Errors are introduced here into the firing soilution you have. The target's own movement is also taken into account when closing on a track.

These errors sometimes cancel each other out and sometimes they compound each other.

[Nisgeis]

Back in the days of Sub Battle Simulator, I used a manual plot and the following forumula for a firing solution: Range to track, at point of torpedo hit, divided by torpedo speed, equals torpedo run time to target. Run time to target X Target speed = distance travelled by target during torp run. plot the distance travelled by target back along its track from the point of impact and when the target gets to that spot you fire the torpedo It really doesnt matter what the aob is . It seems like this Cromwell method is based on the same idea. Based on my experience with Sub Battle Simulator (we're talking hundreds of hours) , I know it is a good method.My question is, what is the importance of the 45 AOB? I really dont think it makes any difference, except that the smaller the angle the smaller the profile of the target at the point of impact. The video and written instructions are great, good job! Joe S

Hi Joe S,

45 degrees is just a point at which the target's lengt is about 75% of what it would be broadside, but you also get the added advantage that 70% of the target's speed gets added to the closing speed of your torpedo, which is a big help. The 45 degrees works even better if you use a spread from aft to bow, as all the torpedoes arrive at the same time.

You can use this method though to attack any angle you want, even from behind.

Thanks for saying about that method you use and yes, it's essentially the same procedure you used to use on Sub Battle Simulator (sounds great :-). The only slight difference is, this is slightly simplified. All we need to find is the ratio between the two closing distances. For that, where you are using distance target travelled, versus distance torpedo travelled, we are taking that equation and simplifying it just a bit.

We are trying to find the angle formed by the two distances travelled, prior to collision for an unspecified unit of time. Your method of using distance travelled by target and distance travelled by the torpedo is great and will give you the correct answer. We can simplify that a bit though, as speed = distance * time for both target distance travelled and torpedo distance travelled, then we can say that the time component of each equation is the same. So, we can substitute it for a value of one. Thus the ratio between distances travelled becomes the ratio between speeds. That simplifies things a bit, as we don't have to work out how far things have travelled, only how fast :|\\.

Do you still use this method? If so, does it still serve you well?

[Nisgeis]

[quote=Munchausen]After thinking about it awhile, I realized this method can be done at any angle, without using the TDC at all ... but (I think) I did it bass-ackwards. Here's what I did, using RR's single mission scenario.

<SNIP Excellent Tutorial>

So, was that bass-ackwards or what?[/quote

Munchausen, that was a brilliant example. You even measured the angles to the ends for extra accuracy :|\\. That's exactly how it's meant to be.

For those that have asked why use the TDC, the answer is you don't have to at all, but if you do put AoB and the bearing into the TDC and ask it what it thinks, it should say zero gyro angle, if it doesn't then you've done something wrong - probably either drawn with the wrong torpedo speed, or you haven't selected the right torpedo speed in the torpedo panel. It may be useful as a double checking aid. It's a bit trickier to work out the AoB in your head, but it's just 180 - target and torpedo intersection angle - the bearing your drawing gives you. That's based on a bit of maths that says all angles in a triangle add up to 180 degrees, so if you know the intersection angle (angle 1) and the bearing you shoot at (angle 2) then the AoB (angle 3) must be (180 - angle 1) - angle 2.

There's only one thing I can add to that Munchausen and that's you could try using the plot navigation course tool to plot your course beyond the target's track. That way you will be able to measure from that, instead of having to draw it.

You can use this method for any attack angle and drawing the speeds over the setup the way you have done really does simplify things, with the use of the course plotting tool, excellent addition! Thanks for taking the time to post that Munchausen! Every bit of discussion helps to generate new ideas. Fantsatic.

[Nisgeis]

OK, I promise to stop spamming now.

[peabody]

One question, should the time be 3 minutes 15 seconds for Imperial? I am getting the wrong speeds. I peeked in mission editor after missing several times. It works but the tanker in the posted single mission keeps turning and the fish go right by him.

Peabody

[doulos05]

One question, should the time be 3 minutes 15 seconds for Imperial? I am getting the wrong speeds. I peeked in mission editor after missing several times. It works but the tanker in the posted single mission keeps turning and the fish go right by him.

Peabody

3 Minutes for Imperial, 3m15s for Metric. It works because...

If you wanted to count the herd by counting the legs and dividing by 4, you could measure 3 minutes (we'll call that d), multipy that by 20 (to get yards/hour) and divide that by 2000(to get knots).
Knots = (d*20)/2000.
Of course, if you're a good mathematician, you say "Wait, we can simplify that!" It simplifies to Knots = d/100.

I'm not familiar with the metric knot, so I can't show you exactly why 3m15s works. But it's the same principle at work.

[Rockin Robbins]

One question, should the time be 3 minutes 15 seconds for Imperial? I am getting the wrong speeds. I peeked in mission editor after missing several times. It works but the tanker in the posted single mission keeps turning and the fish go right by him.

Peabody

You think it's an accident that the demo movie is in a driving rain? http://i196.photobucket.com/albums/aa293/RockinRobbins13/smileys/winky.gif

With a longitudinal spread, turning into the attack is a very simple way to avoid because the topedoes all take the same track to the target. Later, when we crank up the PK and shoot the stern, MOT, bow divergent spread, the torpedoes run side by side to the target and life isn't so easy for Mr Tanker.

A weakness of the John P Cromwell attack is that he's only 45º from the bearing of the torpedo. He's already halfway into the turn to avoid. Electric torpedoes or night/bad weather shots are good here.

[Rockin Robbins]

One question, should the time be 3 minutes 15 seconds for Imperial? I am getting the wrong speeds. I peeked in mission editor after missing several times. It works but the tanker in the posted single mission keeps turning and the fish go right by him.

Peabody
3 Minutes for Imperial, 3m15s for Metric. It works because...

If you wanted to count the herd by counting the legs and dividing by 4, you could measure 3 minutes (we'll call that d), multipy that by 20 (to get yards/hour) and divide that by 2000(to get knots).
Knots = (d*20)/2000.
Of course, if you're a good mathematician, you say "Wait, we can simplify that!" It simplifies to Knots = d/100.

I'm not familiar with the metric knot, so I can't show you exactly why 3m15s works. But it's the same principle at work.
There is no metric knot. Those crazy Europeans, knowing the imperial system is so superior, cannot resist using the knot, because like all imperial measurements it actually relates to something useful (in this case, the circumference of the earth and the number of nautical miles (another more useful imperial unit!) in of one degree of latitude). Kilometers per hour, on the other hand, is so unusually useless, even for a metric unit(!), that they have discarded it in favor of something that actually works for navigation. Imagine that! Using the knot is their one consession to sanity.:rotfl:

3:15 works for metric because the yard is 36" long, the meter is 39.37". It is longer, so you need a longer time to measure it. 3:00/36 =3:15/39.37.

[peabody]

I'll double check, I may have had it set to metric because of the JP campaign, but I was getting incorrect speeds on the tanker. So it is probably my fault. I just remember on another thread one was 3min one was 3min15sec, I just didn't remember which and I did get the correct speed using 3min15sec.

Thanks for the answer.

Peabody

[Pisces]

(other quotes snipped)


There is no metric knot. Those crazy Europeans, knowing the imperial system is so superior, cannot resist using the knot, because like all imperial measurements it actually relates to something useful (in this case, the circumference of the earth and the number of nautical miles (another more useful imperial unit!)in of one degree of latitude). Kilometers per hour, on the other hand, is so unusually useless, even for a metric unit(!), that they have discarded it in favor of something that actually works for navigation. Imagine that! Using the knot is their one consession to sanity.:rotfl:

3:15 works for metric because the yard is 36" long, the meter is 39.37". It is longer, so you need a longer time to measure it. 3:00/36 =3:15/39.37.Actualy the 'naut and (kilo)meter is based on the exact same baseline( 1 quarter of the the pole-equator circumference), just each a different division. Naut's follow the degree-minute division. A kilometer is defined to be one 10,000th of that quarter circle. Or more correctly a meter is one 10 millionth of the quarter-'circle'. Apples and oranges... are both spherical.

3 minutes 15 seconds works because 3600 seconds (1 hour) divided by 18.52 (# of times 100 meters go into a nautical mile) is 194.38 seconds. Rounded to an easy measure that is 3min 15sec.

[doulos05]

[quote=Rockin Robbins](other quotes snipped)
3 minutes 15 seconds works because 3600 seconds (1 hour) divided by 18.52 (# of times 100 meters go into a nautical mile) is 194.38 seconds. Rounded to an easy measure that is 3min 15sec.

Right, I knew there was some sort of mathy ratio behind it, I just couldn't recall what it was. Thanks guys!

[Rockin Robbins]

Actualy the 'naut and (kilo)meter is based on the exact same baseline( 1 quarter of the the pole-equator circumference), just each a different division. Naut's follow the degree-minute division. A kilometer is defined to be one 10,000th of that quarter circle. Or more correctly a meter is one 10 millionth of the quarter-'circle'. Apples and oranges... are both spherical.

3 minutes 15 seconds works because 3600 seconds (1 hour) divided by 18.52 (# of times 100 meters go into a nautical mile) is 194.38 seconds. Rounded to an easy measure that is 3min 15sec.
And that's all fine and good but the Frenchies screwed the pooch (technical term there) and got their measurement way off. The meter ended up having no relationship to the size of the earth at all and now is just a bunch of bars of metal of varying lengths themselves, sitting in various places. They spent lots of time deciding (that means fighting about) which one was the "authentic" meter (who cares? They got it WRONG to begin with:rotfl::rotfl:) and then redefined the meter as a number of wavelengths of a certain frequency of light. THAT'll fix 'em!

So the entire metric system is based on a surveying mistake! Somehow that is very appropriate. Perhaps it's relationship to human error is the most appropriate measurement of all!

[Munchausen]

There's only one thing I can add to that Munchausen and that's you could try using the plot navigation course tool to plot your course beyond the target's track. That way you will be able to measure from that, instead of having to draw it.


I did that yesterday when demonstrating the technique to my daughter's boyfriend. Using the "plot course" tool, the trick is to let your sub turn until rudder is centered ... then you can draw your "hypothetical" triangle and get the offset (lead) angle without even measuring your own course ('cause the tool's line is your sub's course line). You can even continue to close on the target's track ... just so long as you don't change course.

:up: This is certainly the way to go if your TDC is broken ... or you're the skipper of a WWI U-Boat.

[blackbob]

Hi all i have just started with manual targeting with the excellent Dick O Kane method and i've had some fair success so far and i am keen to try this new one but one thing i've a problem with is getting accurate speed estimates my nav map dividers measure in tenths of nautical miles rather than yards and this throws me a bit is this a setting or a mod that i need to get yards ?

[Nisgeis]

Hi BlackBob, welcome aboard! The only reason I can think of for having measurements in tenths of a nautical mile, is if the distance is over 10,000 yards (or 5 nautical miles). Up until that distance, the measurements are in 100s of yards, up to 10,000 yards, over 10,000 yards, the measurments are in tenths of nautical miles.

[blackbob]

Thanks Nisgeis but even if i zoom in the units remain the same i can measure down to 0.1nm i've just realised that i am only patched to 1.3 could that have any bearing (sorry terrible pun)

[Nisgeis]

Perhaps, I'm not sure as 1.3 is a very old patch, you should be on at least 1.4, or SH4 1.5 which is the U-Boat Missions add-on as well (don't call it a patch though, or LukeFF will kill you!)

[blackbob]

I've got the U Boat add on coming this week so i'll stick to shooting things from 90 until it arrives thanks very much for your help

[Joe S]

Hello Nisgeis,

I used that method with Sub Battle simulator because it was the only way to aim torpedoes. The sim did not have a functional tdc, and the manual said to point the periscope and shoot, which only worked for a stationary target. At the time, I assumed that the boat needed to remain stationary, but now , after doing much more work with fire control problems in SHI,2 3 and 4, I believe that your boat could be on the move, as long as your boat and the target stayed on course and did not change speed. I wish I had realized that way back then. Sub Battle Simulator was primitive by today's standards, but the gameplay was the equal of anything we have had since. At any rate, I have not used that method with SH4 due to the fact that we have a functional TDC, which is safe and effective when used as directed. the single most effective element of any fire control solution is target speed, and if you have calculated the target speed accurately you should be able to consistently get hits, no matter what method you use.Theoretically, one could use this "new" method even if your periscope is destroyed if you can get a speed estimate while on the surface, then submerge and wait in ambush, and use the hydorphones to detect the firing bearing of the target. I have not tried it but in theory it should work. Thanks for all your help and work with this, it adds to the knowledge base and gives us additional options. Joe S

[Pisces]

Actualy the 'naut and (kilo)meter is based on the exact same baseline( 1 quarter of the the pole-equator circumference), just each a different division. Naut's follow the degree-minute division. A kilometer is defined to be one 10,000th of that quarter circle. Or more correctly a meter is one 10 millionth of the quarter-'circle'. Apples and oranges... are both spherical.

3 minutes 15 seconds works because 3600 seconds (1 hour) divided by 18.52 (# of times 100 meters go into a nautical mile) is 194.38 seconds. Rounded to an easy measure that is 3min 15sec.
And that's all fine and good but the Frenchies screwed the pooch (technical term there) and got their measurement way off. The meter ended up having no relationship to the size of the earth at all and now is just a bunch of bars of metal of varying lengths themselves, sitting in various places. They spent lots of time deciding (that means fighting about) which one was the "authentic" meter (who cares? They got it WRONG to begin with:rotfl::rotfl:) and then redefined the meter as a number of wavelengths of a certain frequency of light. THAT'll fix 'em!

So the entire metric system is based on a surveying mistake! Somehow that is very appropriate. Perhaps it's relationship to human error is the most appropriate measurement of all!Well, since the earth isn't a perfect sphere but more like a ellipsoid(the reason that 'original french' meter was incorrectly measured), so too a nautical mile lacks concrete definition. Both suffered from the same misconceptions. Infact the nautical mile is now defined to be 1852 meters. Neither is more true than the other.

[Rockin Robbins]

Well, since the earth isn't a perfect sphere but more like a ellipsoid(the reason that 'original french' meter was incorrectly measured), so too a nautical mile lacks concrete definition. Both suffered from the same misconceptions. Infact the nautical mile is now defined to be 1852 meters. Neither is more true than the other. A fine try there. But the Germans themselves say the knot is a better unit, because they chose to throw out the kilometer and use the knot for its usefulness in navigation. Who am I to contradict their good sense?:rotfl:In this case "true" is what works!

Isn't it weird that the Internationals actually succeeded in defining a preexisting measurement with one derived improperly later!? This is a farce, but what do you expect from people who can't properly measure the earth? The nautical mile is at most a little under 1% off at certain places on earth.

Metric measurements are based on non-human parameters (1/10 millionth of the distance between the equator and the pole, 100th the distance between freezing and boiling water, other alien measurements), and as such are not suited to measuring things that humans use, or even humans themselves.

Imperial measurements are based on useful things to do, or on a rough relationship to dimensions of the human body. This makes them much more appropriate for human use. The only thing the metric system has going for it is its decimal nature. But it is intrinsically alien and possibly evil.:doh:

THAT's what Europe needs: an exorcist!:rotfl:

[Bosje]

Stumbled across this thread just now and thought it might merit a bump after RFB 1.52

After four patrols in early 1943 I have come to develop my own attack technique by trial and error. Maybe it is of interest here (being a constant bearing technique at 50-60 degrees)

One of the best ways to prevent duds is by having the torpedoes hit the target at an angle around 60-70 degrees, so the Dick 'O Kane technique results in a lot of duds for me with the perfect 90 degree shots.

the biggest problem with getting a perfect solution at removed angles is that your boat moves during the setup. thus, a perfect solution at 1500 yards on a bearing of 330 will have turned into an unaccurate shot by the time the target gets there (as observed in the original dick 'o kane video I believe, when the boat drifted a bit after cutting the engines) keeping in mind that realistic gameplay calls for continued propulsion to maintain depth, this becomes undesirable

To solve this problem, you can aim the boat so that the angle on the bow will be 60 degrees starboard at your zero bearing. At a target speed around 10 knots, this results in a shot at several degrees starboard angle off your bow, which is still good enough for me. The greatest advantage being that your solution will stay accurate even if you get the range wrong by several hundred yards by slowly creeping up on the target's course line after inputting the solution

still with me?

It's basically still the same constant bearing setup, for a shot at zero bearing (with the torpedo making a tiny turn to starboard) while the entire boat is not on a nice 90 degrees to the target but rather a dud-preventing 60 degrees to the target.

Personally, I find this an excellent way to get some tonnage in the log, even with the early war duds.

If this is all one big unclear mess, I'll provide some screenies :)

[Rockin Robbins]

Works perfectly for me. If you use the vector analysis from the video, which you can do in-game right on the chart, you can calculate the correct lead angle for any angle to the track. Then you can throw the TDC overboard (saves weight for more food!) and go to town!

It does mean that you have to know the torpedo's speed, but that's a minor difficulty compared to the flexibility you get.

[Bosje]

ooohhh just watched the vid (nice one btw, liked the taskswitching and drunken sailor bits :p )
the vector analysis is a new one for me, i'll give it a try on my next contact

but what i was trying to say is this: if you set up the shot on a bearing of 349 at point A, for an aob of 34

it won't be aob 34 on bearing 349 at point B, 1000 yards ahead of point A. right?

argh all this algebra makes my head hurt. i'll play the game and draw some lines, then i'll probably end up coming back here and saying something like 'excuse my utter stupidity'

meanwhile my above mentioned targeting at 0 bearing on 60 degree shots is very satisfying though :)

edit: erm although the vector analysis would suggest that the angles will stay exactly the same while the range decreases, as they all converge at the same point of BOOM

[Bosje]

oh *insert random profanity*

You are obviously correct
i made a very silly mistake: the dot on the map where the target course intersects with the 349 mark on the bearing ring DOES change as you creep closer to the course...
but so does your distance to the target and thus, the angles stay the same, whether you are at 2000 or 500 yards out.
as such, range never even enters into the equasing, except for drawing the plot and putting a random number into the tdc to set the bearing

in fact, shooting at zero bearing means the torpedo has to make a tighter turn at closer ranges (because the turn starts after the torpedo goes underway, leaving less room to properly make the turn) so if anything, it is the zero bearing shot which will get less accurate as you drift closer

firing by vectored lead angle is a gem! I always just took a wild guess, being satisfied with anything between 350 and 10. But now I noticed my attackplot showing a perfect straight line for the torpedo, along the the zero bearing line. torpedo gyro angle is exactly 0 at any range.

if you can forgive a poor fool for opening his mouth, I'll just move on and sink some ships.
After this load of nonsense my addition to this topic can be summed up with:
'60 degrees is also nice'

[Rockin Robbins]

ooohhh just watched the vid (nice one btw, liked the taskswitching and drunken sailor bits :p )
the vector analysis is a new one for me, i'll give it a try on my next contact

but what i was trying to say is this: if you set up the shot on a bearing of 349 at point A, for an aob of 34

it won't be aob 34 on bearing 349 at point B, 1000 yards ahead of point A. right?

argh all this algebra makes my head hurt. i'll play the game and draw some lines, then i'll probably end up coming back here and saying something like 'excuse my utter stupidity'

meanwhile my above mentioned targeting at 0 bearing on 60 degree shots is very satisfying though :)

edit: erm although the vector analysis would suggest that the angles will stay exactly the same while the range decreases, as they all converge at the same point of BOOM

Actually, think of it this way. What is AoB? It is nothing but your bearing from the target. So unless you are on a collision course the AoB will change as time goes by. That's why we use the position keeper. It keeps the bearing and AoB updated all the time. You can see this really clearly in the Dick O'Kane attack. When he's a long way away, he's looking maybe 10º from his bow to see you. That's an AoB of 10º. But just before he gets creamed by the torpedo he's looking almost perfectly abeam to see you 90º from the bow, an AoB of 90º. See how easy it is when you change your point of view?

So why doesn't the vector analysis show this? You're going to need a drink. Maybe several drinks.... The vector analysis is done from the point of view of the torpedo, not your sub. The angles all stay the same for the torpedo from the moment you fire to the moment of BOOM. That's because it is supposed to be on a collision course!:up:

[Bosje]

before i wander off to look for that drink...

http://img396.imageshack.us/img396/2860/angleskn6.jpg (http://imageshack.us)
http://img396.imageshack.us/img396/angleskn6.jpg/1/w1024.png (http://g.imageshack.us/img396/angleskn6.jpg/1/)

i imagined a target with course 60 speed 12, the vector in the top right corner shows me that for a 46 knot torpede, the lead angle is exactly 12 degrees

so i made a plot at around 1100 yards, moved forward a bit and made a plot at 700 yards. what i tried to show is that the point where the target is when you launch the shot varies between both plots, which is why i thought that drifting away would make the solution inaccurate. (which is why i always shoot at a zero bearing plot, resulting in a 12 degree gyro angle for the fish)

but doing the plots in the below screenshot, i found that the angles stay exactly the same. obviously, because the target is closer to the impact point when you launch at closer range, but the torpedo has to travel less far as well,

http://img89.imageshack.us/img89/1885/angles2ub6.jpg (http://imageshack.us)
http://img89.imageshack.us/img89/angles2ub6.jpg/1/w1024.png (http://g.imageshack.us/img89/angles2ub6.jpg/1/)

so yes the colision stays the same, regardless of range. my mistake
(i think we're both saying the same here, but i wanted to show what i learned just now)

edit: yes we are saying the same. '4600 yards against 1200 yards' amounts to the same as '46 yards against 12 yards', so the vectors (point of view from the torpedo) never change indeed

im gonna get that drink now and use that vector thing for real

[Rockin Robbins]

http://i196.photobucket.com/albums/aa293/RockinRobbins13/smileys/thumbsup_weird.gif

Aaronblood is laughing at us. Numbers are like cotton candy to him. I think he BREATHES numbers in his sleep. At will, he can make me look like the idiot I am. I'm just a communicator, not a numbers guy. I can eventually make sense out of them, but numbers are aaronblood's native language.:up:

[starbird]

edit: yes we are saying the same. '4600 yards against 1200 yards' amounts to the same as '46 yards against 12 yards', so the vectors (point of view from the torpedo) never change indeed


This is based on the principle of similar triangles. It says that a triangle with the same interior angles will grow/shrink in proportion. This is true for any triangle.

http://education.yahoo.com/homework_help/math_help/solutionimages/minigeogt/6/1/1/minigeogt_6_1_1_20_50/f-266-5-pr-q.gif

You can see that the triangles QRP and UVP are similar. It doesn't matter if the target is at Q or U, if it is travelling along the line to R or V, the torpedo will connect. The target could be anywhere along the line QP (or beyond Q) and the torpedo in this picture will connect as long as the torpedo is launched at P toward R. Note that the targets at Q and U are traveling at the same speed and same direction.

Also note that this picture doesn't describe what the sub itself is doing (in terms of speed or direction). This picture just describes the torpedo and target tracks.

[Bosje]

well, quite :know:

[Rockin Robbins]

Starbird, I believe that's what would be called a classically elegant illustration.:up:

[Soundman]

Edit..Crap, When I posted this, I didn't realize there were two more pages of this thread I had not read yet!:o

There have been pros and cons for this method stated here. One of the pros I did not hear mentioned is that with this technique, the range you fire from would be increased (over the O'Kane method) and therefore, the ability to be detected by the enemy will be slightly decreased or possibly delayed.

The "O'Kane" method is by far my favorite and as long as the following criteria are met, it's damn near impossible to miss: (1) You have accurately calculated (not estimated) speed (2) The target holds that speed and course.......

As for the above criteria, I find that if I achieve both, I can hit exactly where I aim from very long ranges, but it is very important to nail the speed to within a 1/4 knot. Some will say that's getting picky, but if you are firing from 3500 yds, that type of accuracy in speed is needed and will make the difference between a hit or miss.

Now as for number 2 of the criteria, I have many a time been in perfect position on a DD from about 3500 yards using the "O'kane" setup and painstakingly calculated the speed, only to be detected about the time I'm ready to fire. Therefore, I'm very interested to try this new tecnique on those DD's to see if it aids this circumstance by the ability to fire sooner and a little further away. I'm awaiting the formula and/or the video!

[Soundman]

Hi all i have just started with manual targeting with the excellent Dick O Kane method and i've had some fair success so far and i am keen to try this new one but one thing i've a problem with is getting accurate speed estimates my nav map dividers measure in tenths of nautical miles rather than yards and this throws me a bit is this a setting or a mod that i need to get yards ?

Yes Blackbob, your guess is right. I don't remember for sure, but I remember the measurements being in knots only up until a certain patch (I beleive 1.4), so patch up to fix that issue.

[Nisgeis]

Hi all i have just started with manual targeting with the excellent Dick O Kane method and i've had some fair success so far and i am keen to try this new one but one thing i've a problem with is getting accurate speed estimates my nav map dividers measure in tenths of nautical miles rather than yards and this throws me a bit is this a setting or a mod that i need to get yards ?
Yes Blackbob, your guess is right. I don't remember for sure, but I remember the measurements being in knots only up until a certain patch (I beleive 1.4), so patch up to fix that issue.

That could be it, or it could be your scale. Not sure, but if you are not zoomed in close, then your scales may be in miles. Certainly if you measure over 10,000 yards, the readout on the ruler or divider will switch to miles, but you'd have to be measuring over 5 miles for that to be the case. The increments will then be in 0.1 of a mile.

[Urge]

but it is very important to nail the speed to within a 1/4 knot.

How do you input speeds of less than 1 knot? The readout is only graduated in whole knots unless there is a mod I'm missing.

Urge

[ClearDark]

I have just finished a several hours session practicing O'Kane's and Cromwell's techniques from watching Rick's movies. And i have to say they work like a charm every single time. Vector analysis is really fun doing during the game, i also noticed that certain values never change during these calculations however i also double check by drawing an analysis on the same course of the target. Just abit further away of its non-existence course (since it will be dead by then hopefully :))

On this attack, i launched four fish, all of them hit DEAD ON where the wire was when launched. Nothing beats that.

Speed calcs:
http://www.chimigag.co.il/Images/speedcalc.PNG

Attack plan:
http://www.chimigag.co.il/Images/attackplan.PNG


I have run into several misses when a veteran crew aboard destroyers noticed the fishes tail but in 99% i've had a successful hit in an unprecedent precision.

Thanks alot for sharing this information, these 2 techniques are now by far my most favorite for easy tonnage and without going through the hazardous PK and stadimeter readings.

[Soundman]

Edit..Crap, When I posted this, I didn't realize there were two more pages of this thread I had not read yet!:o

There have been pros and cons for this method stated here. One of the pros I did not hear mentioned is that with this technique, the range you fire from would be increased (over the O'Kane method) and therefore, the ability to be detected by the enemy will be slightly decreased or possibly delayed.

The "O'Kane" method is by far my favorite and as long as the following criteria are met, it's damn near impossible to miss: (1) You have accurately calculated (not estimated) speed (2) The target holds that speed and course.......

As for the above criteria, I find that if I achieve both, I can hit exactly where I aim from very long ranges, but it is very important to nail the speed to within a 1/4 knot. Some will say that's getting picky, but if you are firing from 3500 yds, that type of accuracy in speed is needed and will make the difference between a hit or miss.

Now as for number 2 of the criteria, I have many a time been in perfect position on a DD from about 3500 yards using the "O'kane" setup and painstakingly calculated the speed, only to be detected about the time I'm ready to fire. Therefore, I'm very interested to try this new tecnique on those DD's to see if it aids this circumstance by the ability to fire sooner and a little further away. I'm awaiting the formula and/or the video!

Update: I tried this method last night with great success. Just as I was saying above, I ran into a task force of two DDs. I was able to take out the lead and due to the increased closure rate, by the time he saw the fish it was too late. Also, due to the capability to fire from a longer range, I managed to remain undetected. Of course, the second one turned my direction and I managed to put him under with a down the throat shot. It worked just as I had hoped.

This leaves me to ponder:hmm: , and therefore, a question....Will this method work with any angle calculated other than 45 degrees ? It seems it should, and I'd like to try from say, 25 degrees. In my scenario above, this (may) would enable the ability to fire on the second target shortly after the first. That would avoid the sometimes risky "down the throat" shot. I'll try it later and report my findings.

[Nisgeis]

Will this method work with any angle calculated other than 45 degrees ? It seems it should, and I'd like to try from say, 25 degrees. In my scenario above, this (may) would enable the ability to fire on the second target shortly after the first. That would avoid the sometimes risky "down the throat" shot. I'll try it later and report my findings.

Yes it will work, as long as your gyro angles are still zero.

[I'm goin' down]

What the hell am I doing up at 3:45 a.m. reading about the Cromwell attack? I think it is time to see a shrink...after I watch the video tutorial first thing in the morning after I get up.:dead:

[I'm goin' down]

I set up a Cromwell attack. The ship was approaching from my port side -- the target's starboard side. I set up at a 45 degree angle, and checked it with the bearing tool to make sure my zero bearing was at a 45 degree to the target's track. I checked the speed of the target over a 3 minute interval. I set the scope at 10 degrees and turned off the PK. I sent the range to the TDC. As the target passed the cross-hairs, I fired 4 shots along its length. The torpedoes were set for 20 feet, within the target's depth. I set the AOB at 35 degrees starboard. All of the shots missed. I must have had the speed wrong? Any other ideas? I was set up for so long that I consumed three of RR's Mai Tai's, but I will save victory slice of cheescake for a later date.

[Urge]

Did you watch your fish with the external camera? They might have passed under the ship if you used contact influence (the torpedos had a defect where they ran deeper than they were set for). I generically set my torpedos for 13-14 ft for just about every merchant since I rarely identify a ship( I like to shoot from far away) and I find that I have a low % of torps that pass under.

Urge

[Munchausen]

You didn't mention torpedo speed. The whole idea behind the Cromwell attack depends upon the ratio between target speed and torpedo speed.

[I'm goin' down]

I did not watch the fish on the external camera. I was fixing a Mai Tai in preparation for the party that we expected to have after the merchant went down. I do not think the fish passed under the keel because they were set 5 feet above its draft.

[Munchausen]

I do not think the fish passed under the keel because they were set 5 feet above its draft.

Prior to the official fix, rule of thumb decreed that a torpedo generally ran ten to eleven feet deeper than its setting.

Besides depth, you need to set a torpedo's speed. What setting did you use (fast?) ... and what speed did you use (46 knots?) for calculating your attack geometry?

[I'm goin' down]

Is the lead angle of 11 degrees in RR's tutorial dependent on the speed of the approaching target? Is the same if the target is doing 10 kts. versus 12 kts? If so, I guess you vector it like RR did in his tutorial? Manhausen, I am not sure what geometry you are talking about, plus I am no math wizard.:eek:

[Urge]

I am not sure what geometry you are talking about
Have you read all 3 pages of this thread? Especially nisgeis and munchausen

Urge

[I'm goin' down]

I have read them all. But I must be confused on the concept. Plus, it is an exhausting read. If you have the answer to my post, rather than trying to give me an assignment, please answer the question if you know it. No one has answered it yet.

I think that if a target is doing 9 kts., for example, the lead angle is the angle generated by a track of 900 yds. ending at the 45 degree bearing (i.e. the "0" bearing where I will aim torpedoes.) If it doing 12 kts. then the lead angle is the angle generated by a track of 1200 yds. ending at the 45 degree bearing. And so on.... The faster the target is moving, the larger the lead angle. And vice-versa.

The next issue is how does the speed of the torpedo affect the lead angle. I have seen posts regarding that, and I will review them.

Where is this track? It is on the target's projected course.

If this is correct I need confirmation so I can rest in peace. Once I have the procedure down, I can use it and try to understand the theory while I see it working.

[Nisgeis]

I think that if a target is doing 9 kts., for example, the lead angle is the angle generated by a track of 900 yds. ending at the 45 degree bearing (i.e. the "0" bearing where I will aim torpedoes.) If it doing 12 kts. then the lead angle is the angle generated by a track of 1200 yds. ending at the 45 degree bearing. And so on.... The faster the target is moving, the larger the lead angle. And vice-versa.


Absolutely right.


The next issue is how does the speed of the torpedo affect the lead angle. I have seen posts regarding that, and I will review them.


The speed of the torpedo affects the drawing the same way the target speed does, so when you draw your two lines, one lines is the target's course, where you draw 1200 for 12 kts as you say. The other line represents the torpedo and the length of that is the torpedo speed * 100, so if the topedo runs at 32 kts, then the line is 3200 feet. Another example, for a target of 20 knots and a torpedo of 44 knots, the target line is 2000 feet long and the torpedo line is 4400 feet long. The relationship is that when the target has travelled 2000 feet, the topedo has run 4400 feet, so drawing it out is a way to see where ther start points were.


Where is this track? It is on the target's projected course.


Yes that's right.


If this is correct I need confirmation so I can rest in peace. Once I have the procedure down, I can use it and try to understand the theory while I see it working.

You have it exactly right. The drawing is only to see where the 'start' point is for when the torpedo and target will collide, so, imagine the point where the lines cross being the point where the torpedo has hit the target and then 'rewind' time. Rewind it to a point where a 20 kt target was 2000 feet ahead of the impact point and the other line you have drawn for the 4400 feet for the 44kt torpedo is the point at which the torpedo would need to be fired from in order for the torpedo and ship to collide. You just need to draw the torpedo's line back along the course it was on.

[Munchausen]

The next issue is how does the speed of the torpedo affect the lead angle.

Where is this track? It is on the target's projected course.

If you mean the track of the torpedo, then no. It's actually along your sub's projected course ... making up one side of the triangle.
http://img.photobucket.com/albums/v97/pjcham/SH4/04_torpedo_leg.jpg

A second side of the triangle corresponds to target speed ... it's along the target's course line. The two sides intersect at the point where target track and submarine track meet.
http://img.photobucket.com/albums/v97/pjcham/SH4/05_target_leg.jpg

The third side of the triangle is a line drawn between the ends of the non-intersecting sides. The angle between the third side and sub's course line is the angle (bearing) you use when setting up your crosshairs.
http://img.photobucket.com/albums/v97/pjcham/SH4/06_lead_angle.jpg

The angle between the third side and target's course line is your AOB.
http://img.photobucket.com/albums/v97/pjcham/SH4/08_AOB.jpg

[I'm goin' down]

I am almost there. Nisgeis and Manchusen (I should have anticipated that Manchusen would drop a screen shot display to answer my question [How can the Japanese possibly compete with likes of these guys?]. They are off in "billiant" land again.

Two questions left. I understand how the Cromwell attack works if my boat is not moving.

(1) What if it is moving? Then the distance the torpedeos travel along the lead angle shortens as my boat my boat approaches the target's course.

And, a related question (actually, a subpart of the first question.)
(2) Does this movement have to be accounted for in the Cromwell attack? (I do not think the lead angle is changing, and it remains constant, although I might be wrong about that assumption.)

A special thanks to Nisgeis and Manchusen (again!). I find the screen shots used in Manchusen's step by step examples extremely helpful, and NIgeis, my hat is off to your concise, articulate explanations which are superior to the analyses and writings of many lawyers whose work I have reviewed. (Do you guys love me or what?:D)

"Pass another of those Rockin Robbins' Mai Tai's over here." My crew promised me that I could have three of them before lunch, and I am just about finished with my second one.)

Mai Tai in hand, I glance at Rockin Robbin's tutorial as supplemented by Manchusen's and Nigeis' posts, and turn on the ship's intercom:

"OKAY BOYS, LET'S HUNT SOME MEAT." http://www.subsim.com/radioroom/images/icons/icon10.gif

[Nisgeis]

(1) What if it is moving? Then the distance the torpedeos travel along the lead angle shortens as my boat my boat approaches the target's course.

It doesn't matter if you are moving. As long as both your target's course and your course intersect at some point. The drawing you are using is to work out the relationship between two lengths. In your example of 1200 feet, that represents 12 kts and a torpedo at 44kt with a length of 4400 feet, then this will give you an angle. That's the relationship between the two speeds. If you double the range or halve it, you will still get the same angle - try it and see.

Why is this relevant? Well, because the run length of the torpedo doesn't matter, it doesn't matter how fast you go, or how far you travel towards the target's track, as the ratio is fixed. As long as you have got the course correct, range doesn't matter. Of course it does matter a bit at very long ranges, from the point of view of you can't set fractions of angle on the periscope.

The angle is basically the place you look at that, where it intersects the target's course, is the point at which if you were to fire, anything at that point where you are looking at that moment in time would reach the intersection point of the projected course and the torpedo, at the same time as the torepedo is there. Your aiming point is continuously moving down the target's course and when the target reaches the point along its course where you are looking, then any torpedo fired will impact. Sop, both your aiming point and the target move down the track. It would be very complicated to work out when the aiming point and the target will be the same point, but lucky we don't have to. All we have to do is to wait for it happen.

It's like a continuously calculated firing point, except all the calculations are done. Your range to the target's track is reducing and his range to your track is reducing. It's all been taken care of, as it doesn't matter at what range you fire, you'll know when it's the right time when the target crosses the wire.


And, a related question (actually, a subpart of the first question.)
(2) Does this movement have to be accounted for in the Cromwell attack? (I do not think the lead angle is changing, and it remains constant, although I might be wrong about that assumption.)

You can go any speed you like. It's good for submerged creeping and full speed ahead 21 kts on the surface.

[I'm goin' down]

I am building confidence now and am beginning to like the Cromwell attack technique.

One last question. If you fire slow speed torpedoes, how will that affect the lead angle? If your boat's speed does not affect the lead angle, then it does not seem like the torpedoes' speeds should either. Assuming you alternated between firing fast and slow torpedoes, is the lead angle the same for all? (Subpart of the lead question.)

Another Mai Tai please. Make it a double. Get the cheescake out because when Nisgeis answers this one, we are going to have a party.

Yo ho... ho ho, pirates life for me.

Who sent the message to command claiming we sunk a rowboat?

[Munchausen]

If you fire slow speed torpedoes, how will that affect the lead angle?

A Mk 14 set for high speed moves at 46 knots ... that's why the "torpedo speed" side of the triangle (in the screen shot) is 4600 yards long. But, if you set your torpedo for low speed, it only moves at 31 knots ... meaning, you'd need to shorten the torpedo side to 3100 yards. Try it on a piece of paper and you'll see that doing so will increase the lead angle.

If your boat's speed does not affect the lead angle, then it does not seem like the torpedoes' speeds should either.

Your boat is the focal point for the firing solution. Look at the last screen shot in the series ... notice the smaller triangle? The lead angle is anchored to the sub ... but, in every respect except size, that triangle is "similar" to the larger one. The interior angles are all the same. And the ratio between the sides remains constant.

You can move the sub's position forward or backward and that ratio will remain the same ... as long as the sub is moved along its track (course line). Consequently, you can fire with your sub anywhere along that line and, because the target speed line is always proportional to the torpedo speed line, there's no need to adjust lead angle. It doesn't matter how fast or slow the sub is moving ... what matters is that it be somewhere along that track when you launch torps.

Naturally, if you turn the sub left or right before firing, you've changed the angle where target track and torpedo track meet. Consequently, all bets are off.

[I'm goin' down]

I GOT IT! (i think.)

Yahoo!!


Johnson's corollary to Murphy's law- The odds of the buttered side of the toast falling face down on the carpet increase in direct proportion to the cost of the rug.

[I'm goin' down]

I blew an attack, so I thought I would get some advice. I missed the target because it blew past the cross hairs while I was at kicking my dog, who , without warning, instinctively took a run at my left ankle. The target also changed course, because I was on the surface and it saw me, even though it was 2:00 a.m. and dark out.

To prepare for the missed kill, I prepared a vector at 4800 yds. for a fast torpedo, with a lead of 900 yds. based upon a 9 kt. speed carefully measured over 360 degrees. The PK was off. I set the AOB at 35 degrees port. The lead angle measured either 8 or 9 degrees, I cannot remember which. I sent it to the TDC with my periscope pointed at the corresponding bearing and the range lever pulled all the way to the right (I am not sure pulling the range lever is required?). When I checked the attack map and the PK dial, I noticed a slight gyro angle of about 2 degrees (How do you guys make the little degree symbols?). Now for the question. Shouldn't the gyro angle be 0 degrees? If that is correct, what do I do to correct this?

[Urge]

I'm goin' down wrote...
(How do you guys make the little degree symbols?).
hold down alt type 0176 then let up alt but I can't get it to do it here when I'm replying to a post on Subsim. You could also go to Go To Start/Accessories/System Tools/character Map °


Urge

[Rockin Robbins]

Uh...... it's (testing....testing....damn! I'm running Linux and it doesn't work in this neck of the woods!) isn't it alt-0186?

[Rockin Robbins]

Now, I'm goin' down, let me throw a curve in your direction. With the vector analysis, if you know the target course and speed your course, and the torpedo speed, you can shoot a zero gyro shot no matter what your angle to the track is. Range doesn't matter in the shot, so it is as accurate as a Dick O'Kane shot! No cursed stadimeter need apply.:nope:

You can throw the TDC out the window too! Or just turn it on its side to play poker on.

[Munchausen]

The target also changed course, because I was on the surface and it saw me, even though it was 2:00 a.m. and dark out.

The generic version of the game doesn't simulate night attacks very well. TMO does a better job.

To prepare for the missed kill, I prepared a vector at 4800 yds for a fast torpedo.

If you're using Mk 14s, a fast torpedo moves at 46 knots ... so you should've used 4600 yards.

... based upon a 9 kt. speed carefully measured over 360 degrees.

I use the 3-minute rule of thumb ... don't know how to measure speed using degrees. Please explain.

Shouldn't the gyro angle be 0 degrees? If that is correct, what do I do to correct this?

Yes. If it isn't zero degrees, you've made a mistake (I know ... I set up for a stern shot yesterday and, when I thought I was ready, I noted that the gyro angle was way off ... turned out I had forward tubes selected).

[Urge]

I'm goin' down wrote...
Quote:
(How do you guys make the little degree symbols?).
Urge wrote...
hold down alt type 0176 then let up alt
but I neglected to add -make sure numlock is on and then hit alt, hold down and type 0176 on the numeric keyboard then release alt. It's funny, you can type alt 0176 with or without numlock being on in notepad and it works but it only works with numlock on in Subsims world.

Urge

[magic452]

By George it w°rks :rock:

[Nisgeis]

Don't use the TDC if you are using vector analysis. What you did was to tell the TDC the target was already at the bearing your scope was pointed at, when in fact it wasn't. You also told it that it was at a range it wasn't, consequently the TDC calculated the correct solution to the wrong problem and gave you a lead angle for a phantom target.

Either use the TDC with the correct data and the PK turned on, or don't use it at all!

[Munchausen]

:o Don't use the TDC if you are using vector analysis. What you did was to tell the TDC the target was already at the bearing your scope was pointed at, when in fact it wasn't. You also told it that it was at a range it wasn't, consequently the TDC calculated the correct solution to the wrong problem and gave you a lead angle for a phantom target.

Either use the TDC with the correct data and the PK turned on, or don't use it at all!

It took me awhile to figure out what you meant. I have been using the "Cromwell Attack" under the assumption I was, indeed, setting up for a canned situation. I have always plugged that canned setup into the TDC ... if for no other reason than to confirm my calculations. (Had I not, I never would've noticed that an erroneous gyro angle was due to having selected forward tubes for an aft shot.)

:hmm: After reading your above post, I finally realized that a "zero gyro" attack doesn't require input to the TDC. You just need to make sure target speed is set to zero, target bearing is set to zero, and you've correctly calculated and set the lead angle in the periscope. Zero settings (in the TDC, of all places!) insures the torpedo will go straight out the tube with zero gyro angle. And shooting when the target reaches the lead angle insures the torpedo and target will collide.

The problem is, you can't disconnect the TDC. Like it or not, you're always using it. With PK on, you get a continually updated impact point, depending on the data inserted. With PK off, the geometry only changes if your submarine changes course ... and, even then, the geometry remains the same (as the sub changes course, the TDC adjusts the target's course so as to maintain geometry).

I prefer to plug all the data into the TDC ... it will always confirm my setup (if the setup is correct). I leave PK off ... then wait for the "phantom target" to materialize and sail along my crosshairs.

[old_tex]

I have created a table for periscope settings based on target speed and torpedo speed for use with the Cromwell Method. Let me know if it helps with the setup. :up: Old_tex

http://files.filefront.com/Cromwell+Method+Datapdf (http://files.filefront.com/Cromwell+Method+Datapdf/;12623332;/fileinfo.html)

[Rockin Robbins]

I have created a table for periscope settings based on target speed and torpedo speed for use with the Cromwell Method. Let me know if it helps with the setup. :up: Old_tex

http://files.filefront.com/Cromwell+Method+Datapdf (http://files.filefront.com/Cromwell+Method+Datapdf/;12623332;/fileinfo.html)
A table and the resulting screwups was exactly what got me using the TDC in the first place. Without looking at your table, you have several columns for each type of torpedo and speed, Mark 14 fast and slow, Mark 18, Cutie, and rows for target speed. You look at the intersection and find the lead angle.

The problem is that in the heat of battle you get input saturation and pick the wrong column or row and blow the attack. The voice of experience speaks.:oops: That craziness led me to come up with the Dick O'Kane method of using the TDC, which automatically looks up the correct torpedo speed for what's in the tube and eliminates 90% of the errors committed with a table.

That's also why my rule is no tools outside the game. They only cause trouble!:rotfl:Simple rules of thumb and a minimal number of easily memorized parameters is my stock in trade.

Oh, did I tell you I joined DAM today? Mothers Against Dyslexia?

[old_tex]

Actually, I made it to verify my findings when I graphed out the attack plan. Just use it as a teaching aid. Love the video, by the way. :up: Old_tex

[I'm goin' down]

Sorry, for not posting sooner, but my ISO provider's address changed and my computer did not pick it up, so I was off line trying to figure out the problem.

Okay, I screwed up. Being I am a lawyer, I have learned how not to read instructions. Sheesh.

Manchusen has once again carefully read my posts, and spotted a flagrant misreading by me. I have been measuring torpedo distance at 4,800 yds. for fast torpedoes. That was WRONG, WRONG, WRONG. I should have been measuring 4600 yds.

Admiral Robbins, you are right about throwing out the TDC on the Cromwell attack. The medic has cut me off from Mai Tai's for that error.

Now, why is it that when I set the speed, AOB, mark the periscope at "x" degrees and click on the range button on stadimeter, that the attack map and display on the TBT show a 2 or 3 degree gyroangle sometimes (most of the time.)? When I reclick the range button, the gyro angle does not move. Also, do I need to pull the range lever on the stadimeter all the way to the right?\

Note: I corrected this post after RR's reply immediately below and substituted "stadimeter" for "TDC." I am not sure of the difference.

[Rockin Robbins]

If you're using the TDC method, the lead angle is just one of my simple rules of thumb that will give you a decent approximation of a zero gyro angle. The less than 5 degree angle you get won't mess up your shot, but isn't as aesthetically pleasing as a perfect zero angle.

Yes, I'd pull the range dial triangle all the way down and have an input of about 1450 yards in there. Your range will be further, but with that minimal gyro angle, range is effectively thrown overboard.

[I'm goin' down]

I just viewed, downloaded two copies of Old Tex's, "Cromwell+ Method+Datapdf." One copy will be embossed on the periscope apparatus, and the other is going to the Smithsonian. I suspected someone would calculate the information contained in it, but thought it would be MONTHS down the road, not mere hours. Simply presented, it is practical, yet elegant, precise, and best of all, deadly. Perfect for all skippers. I salute and thank you, sir.

Talk about a Christmas present! I am looking at it!

[I'm goin' down]

[quote=Now, why is it that when I set the speed, AOB, mark the periscope at "x" degrees and click on the range button on stadimeter, that the attack map and display on the stadimeter show a 2 or 3 degree gyroangle sometimes (most of the time)? When I reclick the range button, the gyro angle does not move. Per RR, I pull the range triangle all the way to the right.[/quote]

I do not understand why I am getting a gyro angle other than zero? I used the SCAF mod for attacks using the TDC, and several other mods, but I would not think they are the problem. Does anyone else have this problem? If I have to delete mods to get my gyro angle to zero degrees, then I am robbing Peter to pay Paul, in a manner of speaking. This is driving me nuttier than usual.

(How some women think: When a reporter asked a top paid model why women were so attracted to Aristotle O'Nassis (husband of the late Jacqueline Kennedy O'Nassis, a multimillionaire shipping magnate, and the owner his own island in the Mediterranean along with a large fleet of oil tannkers) who was quite short and not known for his good looks, she paused and replied, "He looks a lot taller when he stands on his pile of dough!")

[I'm goin' down]

°°°°°!!!

Understading the degree key strokes was solved a degree at a time. Thanks for the tip.

[Nisgeis]

Now, why is it that when I set the speed, AOB, mark the periscope at "x" degrees and click on the range button on stadimeter, that the attack map and display on the stadimeter show a 2 or 3 degree gyroangle sometimes (most of the time)? When I reclick the range button, the gyro angle does not move. Per RR, I pull the range triangle all the way to the right.

Actually, I just rethought your question and in the thinking I discovered that you are right and I was wrong in what I said about not using the TDC. If you are putting the same information into it as you are using for the drawing, then the result should be a zero gyro angle shot. So you're right, you should be able to use the TDC to verify the calculation.

Why it's not working exactly, I don't know for sure, but I have an idea. As mentioned earlier you can't get the exact angle either from the drawing, or from the periscope bearing tape. These errors aren't massive, it's only because you can only get an angle to the nearest degree, so shouldn't matter except at range where the target is less than a few degrees wide (like 10,000 yards). But it's possible that these small errors are being magnified by the TDC's calculation. This error should however increase the higher you set the range input, due to parallax, so why it's not changing when you change the range, I don't know.

[Rockin Robbins]

OK, look at the engraved chart on your periscope. Look up the correct lead angle for the target speed and torpedo speed. See how that angle is different from the rule of thumb (10º) in my instructions? Subtract the two numbers. The difference is the strange gyro angle you are seeing.:know:

[Nisgeis]

I took it to mean that I'm Going Down was putting in the target bearing information that he had got from the darwing. If he wasn't he was aiming at a phantom target and that would explain it. If he is using the lead angle from the vector analysis, then it doesn't make sense.

I'm Going Down, point the periscope at the lead angle that you calculated from the drawing and send it to the TDC. That should give you a zero gyro angle.

[Urge]

I regularly shoot at long ranges (6000 yds +) and I find that when using vector analysis I need to zoom in all the way to confirm that my plotted courses and attack angles are dead nuts on. You can lay out a 45° attack plot on the map but when you zoom in all the way it may be off by a degree or even 2 that is not obvious at lower zoom levels. I also go to max zoom to ensure that my targets are centered on the course line I have drawn. All these little errors add up. I have definitely plotted attacks that showed a 1-2° deviation from a zero angle shot and this solution will cure that issue.

Urge

[I'm goin' down]

Okay, I still am having gyro angle problems. I am determined to get to the bottom of it, so I have gone to extraordinary lengths to explain it, during the course of which, I may have stumbled upon the solution (no pun intended).

Here is the information from recent tests I conducted under mock attack conditions.

Test No. 1

Target No. 1 data:

Speed = 10 kts. (entered on the stadimeter);
AOB = 37○ starnboard (angle determined per Old Tex's chart re Cromwell Method of Torpedo Attack) ; and
Range - Range triangle on the stadimeter pulled all the way to the far right.

My boat's data:

Speed = 0 kts.;
AOB = N/A;
Range = N/A;
Periscope Aiming Angle = 0○; and
Gyro Angle per the Attack Map = 350○

Test No. 2
(identical to test no. 1, except my boat's speed has increased from 10 kts. to 11 kts.)

Target No. 2 data:

Speed = 11 kts. (entered on the stadimeter);
AOB = 37○ starboard (angle determined per Old Tex's chart re Cromwell Method of Torpedo Attack); and
Range = Range triangle on the stadimeter pulled all the way to the right.

My boat's data:

Speed = 0 kts.;
AOB = N/A;
Range = N/A;
Periscope Aiming Angle = 0○; and
Gyro Angle per the Attack Map = 349○

Analysis: The only things that has changed between tests nos. 1 and 2 are the target's speed (a change of 1 kts) sent to the
TDC and the gyro angle, which moved from 10○ to 11○. The 1○ change in the gyro angle appears to be dependent on the change in the target's speed sent to the TDC.

Test No. 3

Same settings are input for the target and for my boat, except that the periscope is aimed at 350○ and 349○, respectively. I hit the space bar and sent the range to the stadimeter with the range triangle pulled all the way to the right.

Analysis: The gyro angle was not affected by these actions and did not change in either Test nos 1 or 2. Note, the TDC was still recording the targets' speeds as 10 kts and 11kts, respectively.

Test No. 4

Target No. 4 data:

Speed = 10 kts. BUT THIS INFORMATION IS NOT RECORDED ON THE STADIMETER'S SPEED DIAL; THE SPEED DIAL INDICATES A TARGET SPEED OF 0.0 kts.;
AOB = 37○ (per Old Tex's chart re Cromwell Method of Torpedo Attack); and
Range = Lever pulled all the way to the right.

My boat's data:

Speed = 0 kts.;
AOB = N/A;
Range = N/A;
Periscope = 0○; and
Gyro Angle = 0○.

Analysis: By not recording the target's speed on the stadimeter, it is not sent to the TDC. By way of comparison, the target's speed was entered into the stadimeter in tests nos. 1, 2 and 3, and the speeds entered were sent to the TDC. Thus, the TDC does not receive data on the target's speed in test no. 4 and calcluates it to be 0.0 kts. This appears to cause a 0○ gyro angle in test no. 4

Here are three questions, which will hopefully put the gyro angle issue behind me. (Note, I spent about two hours an hour organizing this post, so there would be no confusion on the part of the readers who have the expertise to analyze and resolve these questions. Unfortunately, I spent far more time organizing attacks using the Cromwell Method of Torpedo Attack only to have the torpedoes I fired miss their intended targets when they followed the gyro angle course created by the TDC.)

If the responses to question nos. 1 and 2 below are "Yes", a simple "Yes" answer will suffice, and the reponse to question no. 3, should be "Not Applicable."

1. Did entry the target's speed on the stadimeter's speed dial in tests nos. 1, 2 and 3 cause that data to be sent to the TDC, which proceeded to calculate the gyro angles at 350○ and 349○, respectively?

Answer: Yes ____ No ____;

2. Is a 0○ gyro angle achieved merely by not entering the target's speed on the stadimeter's speed dial and leaving stadimeter at a setting of 0.0 kts.?

Answer: Yes ____ No ____.; and

3. If sending the target's speed to the TDC in test nos. 1, 2 and 3 is not the cause of the gyro angle of 10○ and 11○, how can I set the the gyro angle to 0○?

Answer (or alternatively, "Not Applicaable, see answers to questions nos. 1 and 2 above."):

_____
My thanks to Urge for his post re entering symbols for degrees.

[Munchausen]

As mentioned earlier you can't get the exact angle either from the drawing, or from the periscope bearing tape. These errors aren't massive, it's only because you can only get an angle to the nearest degree, so shouldn't matter except at range where the target is less than a few degrees wide (like 10,000 yards).

And, if you don't always attack on 45° (C°°L use of DOS* graphics), it's sometimes hard to set your periscope even to the nearest degree ... hard to tell 349° from 348°.

You can lay out a 45° attack plot on the map but when you zoom in all the way it may be off by a degree or even 2 that is not obvious at lower zoom levels.

How many zoom levels do you have? Is your periscope modded for more that two?

Oh, did I tell you I joined DAM today? Mothers Against Dyslexia?

Took me a minute. :rotfl:

EDIT

Just read the above post. Two comments:

1. You didn't include your heading or your target's heading. Without those, it's not possible to tell if you've measured AOB properly.

2. The order you enter data into the TDC is important. I can never remember what goes first ... which is why I always visualize the setup in my head. If, after sending data to the TDC, the result doesn't look right, I go back and enter it again. RR knows the correct order but I find that, as long as you don't move your periscope from computed lead angle (or make any other changes to the setup), you can correct the display by reentering all data a second time.

* Correction: I meant ASCII code (brain fart).

[I'm goin' down]

Let's not get hung up on the AOB, my course or the target's course. The problem appears to revolve around the TDC creation of gyro angle. If we are supposed to enter the target's speed in the stadimeter, apparently it will be transmitted to the TDC. If so, and I believe I have shown it to be the case, I have a problem with successfully using the Cromwell attack technique. If there is a specified order to enter the data to avoid the problems my tests verified, then that could to be the solution.

On the other hand,

Assume, I am at a 45 degree angle to the target's course. Assume that its speed is 10 kts. Assume that I set the AOB properly and pull the range lever all the way to the right. Assume that information is sent to the TDC. Further assume that I plot the lead angle correctly and point the periscope at correct angle and fire when the target intersects it. Why should I bother entering the target's speed in the stadimeter? All it does is give me a gyro angle and screw up the shot? Theoretically, shouldn't the attack succeed even though I have not entered the speed in the stadimeter? After all, we are not relying on the TDC to calculate the firing solution.

I suggest you set up my attack scenarios and watch the gyro angle.

For test no. 1, surface your boat, set your speed to 0 kts, enter 10 kts. for target speed, set the AOB at 37 degrees starboard and pull the range triangle all the way to the right. Keep the PK off. Check the gyro angle. It will be 350 degrees.

For test no. 2, change the target's speed to 11 kts. The gyro angle will be 349 degrees.

For test no. 3, point your periscope at 350 degree at 10 kts. and resend the range. The gyro angle will not change. The same result follows if you point it at 349 degrees at 11 kts.

Now set the target's speed at zero. The gyro angle reverts to 0 degrees.

[Munchausen]

Theoretically, shouldn't the attack succeed even though I have not entered the speed in the stadimeter. After all, we are not relying on the TDC to calculate the firing solution.

As Nisgeis emphasized: yes, that's all you need.

Unless you've already used the TDC and, consequently, it's no longer set to fire a torpedo straight out the tube. Every time you start the game, the TDC is set for zero gyro angle. But, if you enter data that changes the orginal setup, you either need to input the correct data or otherwise set the TDC so it reflects zero gyro.

For test no. 1, surface your boat, set your speed to 0 kts, enter 10 kts. for target speed, set the AOB at 37 degrees starboard and pull the range triangle all the way to the right. Keep the PK off. Check the gyro angle. It will be 350 degrees.

What speed for the torps?

Edit: After trying to set up the described attack ...

LOL, that was fun. I assume you wanted the AOB of the target at the time you fire the torpedo. I tried backing into it but only ended up with a whole lot of triangles ... too confusing to sort out.

It was easy drawing the setup with your 37° AOB at the time the torpedo hits ... I could then determine the target's course and extend that course line backward for 1000 yards (equalling 10 knots). Completing the geometry, I got a lead angle of about 6°. But it also gave me an AOB at shoot time of 30°. So I tried what navigators call the "slip and slide" method ... adjusting the extended course line so it reflected a 37° AOB. But then the line wasn't 1000 yards long anymore. So I extended the line along the newly drawn course line ... resulting in a new AOB.

If you decide to do any more tests, please provide the following data:

Target speed.
Torpedo speed.
Target's course.
Sub's course.

It will save what's left of my sanity.

[I'm goin' down]

I am not at the computer where my game is set up, but I have always set torpedoes on high speed, so I believe they are set at 46 kts. I understand that if I were using slower speed torpedoes, the lead angle would be differerent under the Cromwell attack technique. It does not affect the 45 degree angle of Cromwell attack technique.

I assume you are asking because you want to confirm the gyro angle of 10 degrees and 11 degrees that my TDC calculated in my tests and to set the appropriate AOB. But the target's speed on the Cromwell attack technique and the torpedoes speed only play a role in calculation of the lead angle, and the TDC is not used for that purpose . That is why I believe that speed of the target should not be entered in the stadimeter, as it can only cause gyro angle errors when the TDC assimilates the information.

[I'm goin' down]

[quote]If you decide to do any more tests, please provide the following data:

Target speed.
Torpedo speed.
Target's course.
Sub's course.It will save what's left of my sanity.

There was no target! The sub was heading at 0 degrees. I assumed that this was at a 45 degree angle to the hypothetical target' course. (i.e. with the sub heading at 0 dgrees, we can assume that it is at 45 degree angle to course of the nonexistant target). That takes care of the issue of the Target's course and the sub's course. Target speed was assumed to be 10 kts in test no. 1, 11 kts in test no. 2 and 0.0 kts in test no. 4. Torpedo speed is 46 kts. I do not think anything else is required.

I think this is all that is need to analyze this. I will be interested in Rockin Robbins and Nisgeis take on all of this.

By the way I saw you post re my radio question. All I want for now is to get one station working the right channel. That is my goal for the weekend.

[Urge]

Quote:
Originally Posted by Urge
You can lay out a 45° attack plot on the map but when you zoom in all the way it may be off by a degree or even 2 that is not obvious at lower zoom levels.


Munchausen wrote...
How many zoom levels do you have? Is your periscope modded for more that two?

I am referring to zooming in on the nav map. Sorry if that wasn't clear, it made perfect sense in my head but I guess it didn't translate well.

Urge

[I'm goin' down]

I have cleared the deck and I am going to hunt ships and use the Cromwell attack technique, with the lead angle determined per Old Tex's chart re Cromwell Method of Torpedo Attack, and I WILL NOT INPUT THE TARGET'S SPEED IN THE STADIMETER. I will report back after the mission. Take her down.

My next assignment is the Radio Mod.

[Nisgeis]

The sub was heading at 0 degrees. I assumed that this was at a 45 degree angle to the hypothetical target' course. (i.e. with the sub heading at 0 dgrees, we can assume that it is at 45 degree angle to course of the nonexistant target).

I think this is where you are going wrong. The AoB that you enter is the AoB of the ship currently. The 45 degree intersection means that at the point of impact the target's Aob will be 45 degrees to port or starboard. What I think you are doing is telling the TDC that the target already has a 45 degree AoB at the shooting bearing. This will make the TDC think that the target has a different course, which takes the target further away from you, so it tries to compensate by making the torpedo head a bit to the left or right to compensate.

To properly get the AoB, you need to calculate the angle between your line of sight to the ship. If you want to use the TDC to verify your shooting calculation, this means that you will need to enter the information as it will be when the target crosses the wire. That mean you need to measure the angle between your line of sight and the target's course on your drawing. That is the target's AoB at the time to shoot. You then put this info in, at the shooting bearing, with teh target's speed and it should give you a zero gyro angle shot.

If you are going to use the TDC in such a way though, it's no longer a simple drawing method and you are starting to use the TDC the way it is meant to be used, except with the PK on and then you are fully manual targetting. And then you can use spreads, which are a much better way to shoot torpedoes, spreading from aft to bow you'll get a whole lot more bang for your buck. You're only a step away :D. Keep going. I admire your perseverance!

[Nisgeis]

I am referring to zooming in on the nav map.

That's a good tip, gives you a bit more accuracy.

[Rockin Robbins]

Nisgeis has hit on half of it. The AoB is VERY important here. Use the rule: 45º minus the lead angle.

And the rule of thumb for a 10 knot target (or anything close to that). Out of the air, produce a 10º lead angle. For a target moving from right to left, your shoot bearing should be 10º then, not zero as you shot. I don't get excited about anything less than a 10º gyro angle, even at extreme range.

With this example, you would set the TDC for speed: 10 knots or whatever the target is going. Set AoB at 45-10=35º port. Now the torpedo will go up the approx zero degree bearing to hit the ship. You're shooting at 10º. When he gets to zero, there will be a surprise waiting for him. I hope he's happy with his Christmas present.:yep:

As Tim Tebow, you are throwing the ball not to where the receiver is, but where he will be when the ball arrives. Did I just lose three-quarters of the world or what?http://i196.photobucket.com/albums/aa293/RockinRobbins13/smileys/lotsa_greenguys.gif

[I'm goin' down]

No news yet. I tried two attacks on task forces. I did not input the target's speed on the first attack, but I did input it on the second one. I will stick with the second alternative for now, as not entering the target's speed may have been a bad idea.

The first attack. I set up too late, so I decided to try a reverse Cromwell attack, firing at a carrier at a 45 degree angle as the task force was pulling away rather than closing. A destroyer got in the way and absorbed two of the four torpedoes, and the other two missed.

The second attack. Again I set up too late. Again, I set up for a reverse Cromwell attack as the task force pulled away. My sub was detected, rammed, and depth charged. I fired four torpedoes at a carrier at the requisite lead angle. I had previously set the speed and range, but I did reset the AOB. All four shots missed. I checked the Attack Map. While reseting the AOB to deal with the fact that that target was pulling away, the task force, including the target, had turned 60 - 70 degrees to port (away from my sub), and were almost parallel to my boat, presenting minimal target aspects. The shots missed, but not by much, which was a pleasant surprise. The course shift by the target likely accounted for the misses.

I have saved the second attack a point where I was closing for the shots, so I can replay the attack and see if I can avoid detection and get properly set up for the Cromwell attack or if necessary, for what I call the reverse Cromwell attack.

[Munchausen]

While reseting the AOB to deal with the fact that that target was pulling away, the task force, including the target, had turned 60 - 70 degrees to port (away from my sub), and were almost perpendicular to my boat, presenting a minimal target aspect.

:hmm: Perpendicular? Wouldn't that present the maximum target aspect?

[I'm goin' down]

Darn, your mama taught you how to read.

I saw parallel in my head but I typed perpendicular. I just corrected the post. And next time I will try to sneak something past you....

[AngronIsAngry]

First things first: Thanks for the method Nisgeis and thanks for the tutorial Rockin Robbins (hope I got the credentials right)

The most helpful to me in the tutorial was the part about the vector solution on the NavMap. It was helpful to the point of me forgetting about approaching at certain angles and just measuring the given situation as well as forgetting about any TDC Input. At best I identify the target for getting torpedoes running depths.
If this is just my method to avoid "driving like a drunken sailor" or if I'm just to drunk to drive at all, that's a different topic.;)

I'm thinking that it could be helpful to reference the explanation behind the vector solution and its demonstration in the stickied tutorial thread, since Dick O'Kane and John P. Cromwell are the two extreme cases of the same solution.
Having it covered here under 4 pages of questions and ty's might not be ideal.

[Nisgeis]

First things first: Thanks for the method Nisgeis and thanks for the tutorial Rockin Robbins (hope I got the credentials right)

Yes you did. Initially RR didn't want to include the vector analysis as part of the tutorial, but thankfully I managed to talk him round. If you're drawing the vector analysis, you're only a short step away from using the TDC for any situation that might come up.

[I'm goin' down]

OK, look at the engraved chart on your periscope. Look up the correct lead angle for the target speed and torpedo speed. See how that angle is different from the rule of thumb (10º) in my instructions? Subtract the two numbers. The difference is the strange gyro angle you are seeing.:know:

As posted previously, I had saved an attack on a task force, so I could replay it until I set it up correctly for an attack using the Cromwell attack technique. I kept screwing up the set-up until I replayed it today for the 5th time. I fired four shots at a carrier at 3300 yds with a AOB of 45 degrees. It wa or 6th time. The task force course was to closing on my port side I set my lead angle at 352 degrees. The carrier was travelling at 11.5 kts. and I was using 46 kt. torpedoes. According to Old Tex's chart the AOB should have be between 351 and 352 degrees. I fired the first two torpedoes towards the carrier's bow, and the last two towards its stern. The first two hit amidships and the last two hit near its stern. I noticed the gyroangle was not at 0 degrees. My ship was dead in the water when I fired (that is how I know the distance to the target was 3300 yds.), and there was a gyroangle showing on the Attack Map at +1 or +2 degrees (I did not have time to look to see the precise degree of the gyroangle.) Assuming the TDC somehow computes a slight gyroangle (even though the PK is not turned on), with my crosshairs pointed at 352 degrees when I record the range to the Stadimeter, should I adjust the setting of the crosshairs for purposes pulling the trigger on the torpedoes (not for purposes of resetting the range on the Stadimeter) because the gyroangle is not 0 degrees, or should I calculate lead angle by starting at +1 or +2 degrees and send the range to the Stadimeter based upon the new periscope readingr? The purpose resetting the crosshairs is to compensate for the fact that the gyroangle is not at a 0 degree bearing. If that is the correct thing to do, I shoulld adjusted the crosshairs to a bearing of 353 or 354 degrees undler the assumption that the correct gyroangle of -8 degrees calcuated from the gyroangle of 1 or 2 degrees rather than 0 degrees.

Secondly, I set up this attack well ahead of the task force, and I used Silent Running with a speed of 3 kts. And then I stopped the sub. I fired my torpedoes and shortly after. Then my sub was picked up by destroyers and sunk. Usually they find my sub before I fire. Can they locate subs that use silent running or that are dead in the water? What's the deal?

The four shots that hit the carrier were set at 25 feet. They passed under an escort that was guarding it starboard side. The carrier sunk, and I saw it go down. Unfortunately, I missed most of its death throes because its view was blocked by the escort and my camera did not trigger because it went down slowly. Too bad. It is the first time I sank a carrier. During all the commotion, it turned out that a destroyer caught fire, but I am not sure how that happened. Maybe one of the torpedoes hit it, but that is unlikely because they were set to run deep.

[Nisgeis]

At the impact point at 45 degrees, the target's AOB at the time of firing will be 180 - (135 + number of degrees from zero your shooting point is). So, if your firing bearing is 352, and the target's course will intersect yours at at the 45 degrees, then the target's AOB (which you put in the TDC) is 180 - (135 + 8) = 37 degrees to starboard.

It's 180 because there are 180 degrees inside a triangle, so if you know two angles (the intersection of both of your courses is 135 degrees (90 plus 45) and the angle you are looking at is the second angle, then the angle between the target ship's course and your line of sight is the remainder and that's the AOB.

You can also measure this from the map, but it's easy just to calculate out the 180 - 135 part as that's a constant and just use 45 - offset angle to work out the AOB. Putting in an AOB of 45 will make the TDC thing the target is on the wrong course and will give them a slight left gyro angle order to compensate.

I wouldn't recommend adjusting your fiirng bearing to make the gyro angle order become zero, you'll just be making innacurate data worse.

[Rockin Robbins]

I'm going down, I think you're confusing terms and getting confusicated there. If you are then lots of people are and we need a new tutorial that is beyond my present means to produce. I could, however, make some diagrams defining all the terms.

I say this because I know you didn't mean Angle on the Bow when you said that in your last post. And that explained a lot of the problems you've been having. I'm going to have to play with some new drawing programs because Corel Draw 4 doesn't like Windows XP, so it will take a little time, but I'll get it done.

@Angron: you have it precisely correct, even more than you know. Nisgeis first came to me with an idea for an attack from 45º ahead of the target. First we talked about the possible reasoning to attack from that angle and agreed that there were two really big advantages and a third pretty good idea:

when you are 45º ahead, you could actually shoot from ahead of the escorts
while the torpedo is on the way to the target, they are approaching each other, actually making the shot more accurate because the angular size of the target is increasing as it approaches the submarine.
a long distance shot is then more accurate and the target has less time to react because the closing speed is 70% of the target speed plus the 46 knot speed of a high speed torpedo.After we agreed on the possible advantages, I got pretty excited and proceeded to work out the procedure according to my formula: no outside tools, simple rules of thumb, no calculations you can't do in your head, extreme simplification in everything.

And he picked out the name. He liked the idea started in Dick O'Kane of naming techniques after prominent submarine captains. We narrowed our choices to two and he picked John P Cromwell, as a captain earning the Medal of Honor for his personal sacrifice, not his skill as a top producer. Captain Cromwell chose to die rather than risk giving away the secret plans he knew of a coming invasion.

Then we had a train wreck. After I explained the procedure I would put into the video (quite proud of myself there, you can imagine), he came back with "but that's not what I think of when I think of the John P Cromwell Technique at all." He told me about the vector method of making sure you have a perfect zero gyro every shot. I regurgitated all my usual bull about my tutorials being for beginners with the motto that if my cat can't hit the target the tutorial is no good.

He said, "Try it, you'll like it." So I tried it. And I liked it. So I produced the video with a complete illustration of the vector analysis method along with my "rule of thumb" method along side. Which all begs the question "what next?" Gutted is out there thinking "I tried to tell you that a year ago!" But I was pretty single minded then about making tutorial for beginners and wasn't looking beyond that point. Now we can use the vector analysis method to take skippers beyond the beginning.

Because with vector analysis, range doesn't matter, no matter how long the shot, or from what angle. Any time you shoot with a zero (or in practice, a near zero of +-15º or so) gyro angle, you hit your target even if your range calculation is way off. You're not even entering range into your TDC.

So to answer your question, the original idea is Nisgeis', the name is Nisgeis', the vector analysis is Nisgeis', the rule of thumb method is mine, the tutorial is mine. The score: Nisgeis 3, Rockin Robbins 2.

[I'm goin' down]

I made a mistake in communicating. The AOB was set to 37 degrees, not 45○. My apologies to Rockin Robbins, who first caught the mistake.

I read Nisgeis' last post. I understand how the 135○ angle is derived, although it took me awhile to conceptualize it. And I undertand that the AOB is calculated after the lead angle is input (in my example the lead angle was 8○) into the vector analysis,. Thus, the AOB in my attack on the carrier was 37○ [180○ (representing the number of degrees in a triangle) - 135○ (90○ + 45○)[representing the angle of intersection between the carrier and the torpedoes when attacking at a 45○ angle] - 8○ [represnting the lead angle per Old Tex's chart, or alternatively, calculated using the mehtod described in RR's tutorial]).

Having said all of that, it still does not account for the slight gyroangle on the Attack Map. If the slight gyroangle will not cause the torpedoes to miss, I will ignore it. However, if it will generate missed shots, then I want to compensate for it, even if it means adjsuting the firing point by one or two degrees. The problem is not in the calculations, it is in the gyroangle that the TDC generates on the Attack Map, since the torpedoes follow the gyroangle and not a 0○ bearing.

Assuming I am with you guys on an intellectual level re the vector analysis method of pinpointing the firing point, AOB, etc., I am trying to focus on the gyroangle issue created when the gyroangle is not 0○. It may be a non issue and if it is, fine with me.

[Munchausen]

Having said all of that, it still does not account for the slight gyroangle on the Attack Map.

Errors in gyro angle can be caused by slight errors in data dialed and sent to the TDC:

Target speed
AOB
Bearing (periscope adjustment)

Even if you measured a dead-on accurate speed for your target, the speed dialed into the wheel might be off by a tenth of a knot. You could be off half a degree in dialing in AOB ... and the same for adjusting your periscope before taking a bearing.

All of that can add up (:hmm: I think RR said all this before ... but buried it in the middle of one of his longer explanations).

[starbird]

The TDC takes into consideration other issues for firing a torpedo, other than just solving the attack triangle. This is based on the real TDC, but it seems that the simulated one takes at least some of these into consideration. I'm not sure how exactly the torpedos are modeled in sh3 or 4. There is a time for the torpedos to reach their cruising speed, turn radius is different depending on which way the gyro is set, depth can play a part too, etc.

http://hnsa.org/doc/tdc/tdc01.pdf

This section of the TDC manual talks about the problems it solves. The gyro angle is set depending on distance to the target and its speed, and takes into account torpedo reach (before it starts turning via the gyro), and the turn radius.

So there shouldn't be too much concern when using the TDC compared to the simple vector analysis 'hip' shot. The TDC can be more accurate, but its not as important for near 0 gyro shots.

The mark 8 angle solver (banjo) does the same thing, but it uses a plate that the solver arm rests on to show the proper gyro angle. There is a different plate for each torpedo type, and the speed that the torpedo is fired at. I havn't been able to find a good picture of these plates.

I don't know if these factors are responsible for the slight error that is seen, but its something to think about.

[I'm goin' down]

Munchausen's post and Starbird's to a lesser degree have convinced me that slight errors inputing date create the gyro angle that is off by a degree or two. I can live with that. I just could not figure out the reason why it was not a perfect 0 degrees, and now I believe the reason has been explained. Thanks for putting up with my persistence.

[sckallst]

Ordered to patrol the Bismark Sea west of Rabaul in Jine 1942, I and the rest of teh crew of the S-42 head north out of Brisbane. I decide to be aggressive and transit the narrow channel between New Britain and New Ireland in darkness, rather than burn precious fuel by running all the way west of New Britain and then back east to my patrol area.

As dawn breaks we clear the north entrance and I prepare to order a turn west, we first dive for a routine check of the hydrophones. Contact! She's far off in the distance, but a half hour of taking bearings tells me I should have a shot at an approach. I pop up to scope depth and finally make her out. Damn, she's a big modern tanker and she's hauling ass into Rabaul, but I should still be able to get a shot. Make the turn to intercept and a few minutes later realize to my dismay that she has turned herself to make her final run into port. I recompute and figure out my only shot will be a prayer. I decide to let her go.

Not a good start to the day.

The day wears on as we head east to what I've decided will be the fishing hole. Routine sound checks pick up a few long range contacts, but the plots indicate we have no real chance at catching them. Just as I'm about to surface after the latest disappointment, I sweep one more time with the hyrophones and pick up another very faint contact, 20 degrees off the starboard bow. One humdred fifty feet down, doing 2 knots, we turn right at her and listen. It's 1734 hours.

Five minutes pass. No bearing change, still very faint. Ten minutes pass, still no change. Twenty minutes pass, and finally a one degree bearing change. But she's getting louder with every reading, and she's coming right at me, course 075. This should be like taking candy from a baby. I'll just turn and glide in at 1 knot, putting a few in her side as she passes using the good old O'Kane method.

She keeps on coming doing 11 knots. She s a big old split merchant, 8000 tons worth, and I know where she'll be before she does. I listen to the gramophone like Lecter waiting for Deputy Pembry. At around 4000 yards, she slows, then accellerates. Damn it, another one is going to turn and get away. For a few seconds I panic, but I realize that I'm still OK, at least to try to chase her down. She's turned to the southeast, but having set myself up for a 110 degree shot, I speed up and turn to lag her just a bit, hoping to get myself in position for a new shot. If I want to have any chance at all iIve just got to steam along this line and hope I can figure out when and where to shoot.

A couple of visual readings and a few by sonar and I've got her pegged again. But how am I going to hit her?

Suddenly, I remember overhearing a conversation in the officers club in Brisbane. A couple of the old salts were discussing something they called the Cromwell method. I yell to the plotting team: "We're going to do some vector math!" 36 knot torpedo. 11 knot target. Maybe these drawing tools are useful after all.

She's steaming away from me, and I won't have as nice an attack angle as I want with an AOB of about 150, but the math says that if I lead her by 6 degress, I should hit. She's over 2200 yards out, 25 degrees off my starboard bow, and her lead is growing. I slow down one more time to minimize my scope wake. Up scope! I point the scope to 324, press the bearing input, then turn her back to 330 and wait. Her bow crosses the wire. I wait a beat. Fire One! Fire Two! A couple more beats. Fire Three! Down scope. With a 30 degree gyro angle I probably should have thrown in a "Hail Mary" with each fire command, but at this AOB and at her speed I barely had enough time to fire fast enough as she crossed the wire.

I hold Four in reserve, lying to myself that I'll need it for a coup de grace. If this doesn't work, I'm gonna give those guys in Brisbane the business. If I make it back to Brisbane, that is.

The torpedo run seems like it's taking forever. I know I missed. It's just taking too long and I'm too juiced up to find the wiz-wheel and figure the run time. It doesn't help that I did all my training with those new fast running fish and I'm stuck here hunting Japs with these 36 knot antiques. I raise the scope to watch a juicy target sail off into the fog.

The scope breaks the surface just as the sound man rings out: Torpedo Impact! All I see is a big splash. Then again: Torpedo Impact! Then a couple more beats. Torpedo Impact!

Holy cow! I think I owe those guys in Brisbane a beer.

*************************

It's was all so simple, I'm just wondering why I never thought of it before. Just one of those moments where you remember why you play the game.

[sckallst]

Yeah, the above is NOT a "classic" Cromwell attack as outlined here, as I was most certainly NOT a zero gyro shot. But the basis for what I did grew out of the basic Cromwell idea, then I just did some quick drawing and figuring to make it work in a situation where getting in position for a zero gyro shot was not feasible because I wasn't smart and fast enough to get there. It all comes down to the vector analysis, and having good numbers on your target.

I never turned the TDC on in this run up, as I was setting up for an O'kane type attack and with frakkin' lock thingie wouldn't work for me so I had no target input in the bucket of bolts anyway. But once I knew where the target was going, the vector analysis works like a charm even for bigger gyro angle shots. You just have to hope the fish cooperate.

And yes, for close readers of the above, I screwed up port and starboard. But it's late and I was in Mickey Spillan mode. So shoot me.

Anyway, the cool thing about this game is figuring out new ways to skin a cat, then catching hell for waking up your wife because you're yelling like a schoolboy when your plan all comes together.

[Munchausen]

:up: Vector analysis opens up a whole new ball game ... bring on WWI!

[Rockin Robbins]

And vector analysis is so darn fast! It's perfect for when that Dick O'Kane suddenly goes bad because the target changed course.

[I'm goin' down]

Just to show the consequences of learning manual targeting, the O'Kane method, and the Cromwell attack technique, my boat embarked on a new career using Fred's pre-December 7, 1941 career start mod, so the crew could listen to all of the pre war and early war radio braodcasts. However, I neglected to change the game settngs, and did not realize the TDC was set to the game's default "automatic" settings until my boat was on patrol near Honshu. I figured we would have some fun before returning to Pearl where I could change the game settings. When I finally tracked down a solo freighter, we fired four torpedoes at 800 yards - a broadside shot - when it passed the 345 degree periscope bearing (the angle used in the O'Kane tutorial by RR). I did not wait until the torpedo firing light was green--it was yellow. I missed all four shots aft! Well, at least the radio is working. Now I just have to insert music in the radio mod!:p

[Rockin Robbins]

OK, don't shoot me, it's been awhile since I had a drawing program actually working: since I had CorelDraw 4 on Windows 98SE. It was a fine program and I knew it well. Now I've stumbled on a free (<CorelDraw which is.... OH! If you want to buy it you also have to buy junk you don't want. Only $429!) program that seems to have all CorelDraw's tricks for free, Inkscape. Seems to me I also saw it available for Windows. Yup! http://sourceforge.net/project/showfiles.php?group_id=93438 hope that also gives the Windows version. Very useful.

So I used Inkscape to kudge out a line-drawing of the terms and methodology of the Cromwell Technique. I'll also do one that totally explains vector analysis and not make it at all about the John P Cromwell Technique, so people can see that it really is a universal solution that deserves to live apart from any straightjacket the Cromwell Technique might leave you the impression it is wearing.

http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/JohnPCromwelltargeting.png

Doncha just love exporting vector drawings as png files with transparent backgrounds? Stand by whilst I place a background. I'm assuming you know whether the AoB is starboard or port but I could add that if anyone thinks it would help. Linux is a wonderful (free!) thing!

[I'm goin' down]

Darn it! Rain on my parade!! I just finished memorizing Old Tex's chart which dissected the AOB and lead angle to account for various target speeds when using the Cromwell attack techniqe. And what happens? Rockin Robbins presents a drawing showing wonderfully simple vector analysis that simplifies the techique by using on two lead angles. AAARRRGGGHHH!

[I'm goin' down]

Having failed at Automatic Targeting (see post 162), I returned to based and changed the setting to Manual Targeting and returned to sea, where I sunk a large modern passenger ship using manual targeting and the SCAF mod to get the correct aspect ratio and range (See Hitman's tutorial and my comments in a separate post re SCAF as a means to shortcut some of the steps). Now, I will turn my attention the John Cromwell attack technique if the occasion presents itself. Let's try the vector analysis at another AOB, rerun the calculations and see what happens .....

[Rockin Robbins]

Thanks to Nisgeis, Hitman, aaronblood, gutted, Capn Scurvy, Old Tex, tale, Rocks n' Shoals, WernerSobe and others we have such a great bag of tricks to ruin our targets' day!:sunny:

[Rockin Robbins]

And here you go, folks, a nice 3x5 card size (I can make the vector version available on Filefront if that will help) chart of the steps for vector analysis shots. Note that this will work for any angle of own course to target track with a perfect zero gyro shot every time without fail. This alone is worth the cost of admission!

http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/VectorAnalysistargeting.png

Clear as mud? Any corrections, additions, deletions, bad jokes, etc?

[I'm goin' down]

If you want to prove to your friends that your are nuts, give them a copy of the 3 x 5 card and tell them it is the best Christmas present you have ever received. I printed 100 of them, and am having them made into stocking stuffers.:D

[I'm goin' down]

Post 163 gives rules of them for target speeds of <15kts and >15kts. If the target is travelling at 15kts, is the lead angle 15 degrees?

[Hydra]

RR, for clarification, if you were moving away from the target path (point of impact) would you set the AOB to 180 to use rear topedoes and aim the scope to 180 - lead angle?

[I'm goin' down]

Rockin Robbins, now you even have Hydra getting his heads around it.

[Rockin Robbins]

RR, for clarification, if you were moving away from the target path (point of impact) would you set the AOB to 180 to use rear topedoes and aim the scope to 180 - lead angle?

No you wouldn't. Your shoot bearing would be 180º to get the torpedo out of the aft tube. But everything else would be the same. You'd calculate the lead angle, move the periscope that number of degrees toward the target from the 180 bearing, in this case back to 170 if your target were at 15 knots or less. Hit the send range/bearing button to send the torpedo up that line and shoot as juicy parts of the ship cross the wire. You can break out the mai-tais before the torpedoes hit. You have a sinking on order by FedEx!

[Hydra]

Thanks RR. So AOB remains zero and the shoot bearing (180 degrees plus or minus lead angle) to use aft tubes?:hmm::hmm::hmm::hmm::hmm::hmm::hmm::hmm::hmm :

[old_tex]

Thanks RR for the 3x5. I have it next to all the other navigational widgets on my desk. Great Work! :up: Old_tex

[I'm goin' down]

So we apply the Cromwell technique at a 45 degree angle to the target's course. Do the same principles apply (i.e. torpedo speed and target speed) when calculating the lead angle if you were attacking at 10 degrees? I assume at a 10 degree angle, the AOB for the target would be set at 10 degrees.

I pasted your 3 x 5 on the periscope, right above Old Tex's masterpiece. My son suggested that I tape it to my forehead.

[I'm goin' down]

None of us should lose sight of the fact that information in this thread is remarkable and groundbreaking. It's right up there with Hitman's tutorial on manual targeting applying the target's aspect ratio, the related SCAF mod, Werner Sobe's tutorial on attacking via radar, Rockin Robin's tutorials on the Dick O'Kane method, and Lane's insane thread that shows scantily dressed photos/drawings of models pasted on the captain's office walls, doors, book covers and desk photos. There are some high I.Q.'s at work here and their imaginations are running wild. When will someone launch a submarine to the moon?:up:

[starbird]

So we apply the Cromwell technique at a 45 degree angle to the target's course. Do the same principles apply (i.e. torpedo speed and target speed) when calculating the lead angle if you were attacking at 10 degrees? I assume at a 10 degree angle, the AOB for the target would be set at 10 degrees.

Yes. Just draw your vectors with the correct angle. I see RR changed his card to say any angle, rather than 45 degrees. :) Any angle works, ahead or behind the target.

[Rockin Robbins]

So we apply the Cromwell technique at a 45 degree angle to the target's course. Do the same principles apply (i.e. torpedo speed and target speed) when calculating the lead angle if you were attacking at 10 degrees? I assume at a 10 degree angle, the AOB for the target would be set at 10 degrees.
Yes. Just draw your vectors with the correct angle. I see RR changed his card to say any angle, rather than 45 degrees. :) Any angle works, ahead or behind the target.

No, there are two cards: one for the John P Cromwell method, which always uses a 45º approach. And the second card is for the vector analysis method, which can use any angle, including the 45º angle of the John P Cromwell attack. They are two different cards.

The vector analysis card was separated from the Cromwell card because It needs to be liberated from the shackles of fixed angles and allowed to work as the versatile tool it is.

[Munchausen]

The vector analysis card was separated from the Cromwell card because It needs to be liberated from the shackles of fixed angles and allowed to work as the versatile tool it is.

:up: Looks good. Slap a "Property of USN" on it so I can print it out and put it in my notebook.

[cleverusername]

Aren't you guys doing exactly what the TDC does: calculate lead angle for the torpedo, except by hand? Why not just use the TDC? Or am I mis-reading everything (probably)?

e.g. with the TDC:

Target course is 090T. You have your scope pointed at 330T. That means AOB when the target crosses your scope is 060 Starboard.

Enter bearing 330T, AOB 60 starboard, and target speed into the TDC.

PK off since you're aiming at a ghost ship. If you want a zero-gyro shot, turn your sub until the gyroangle indicator on the TDC reads 360 degrees.

Wait until target crosses the hairline, and shoot! No need to calculate lead angle by hand.

[Nisgeis]

Aren't you guys doing exactly what the TDC does: calculate lead angle for the torpedo, except by hand? Why not just use the TDC? Or am I mis-reading everything (probably)?

It's sort of doing what the TDC does backwards. The TDC will tell the torpedoes where to go if we shoot now as it predicts where the impact point will be. The vector analysis is only for a situation where we want the impact point to be in a specific place and want the torpedoes to go straight out.

The advantage to it is that it is largely range insensitive, except with extreme ranges, whereas the larger the gyro angles are, the more important the range is (due to the torpedo's reach, where it travels a certain distance, before it changes course to its gyro angle order). With a large gyro, the torpedo sort of bends back on itself and will only intercept a target on that course at that speed at that range, give or take a few hundred yards.

[Rockin Robbins]

While I'm at it and running my Linux installation I took about five minutes and schlepped out this 3x5 card for the Dick O'Kane technique. Now that you have all of them in the same place, you can see how alike they are, eh?

http://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/DickOKanetargeting.png

They are all near zero gyro attacks and relatively insensitive to range. The vector analysis attack is completely insensitive to range as long as the torpedo can get to the impact point.

They are all longitudinal spread patterns, that is the torpedoes all advance toward the target in a single line. They use the motion of the target and their timing to hit different parts of the target.

All these attacks can be set up in their entirety a half hour before you want to shoot. Then you maneuver your boat into position and shoot at your leisure. There is no hurried mashing of information into the TDC before everything goes stale. When it's time to shoot you have nothing to do but mash the button at appropriate times and sip your mai tai.

Look how far we've come in a year! And look at all the people who have contributed. None of this is purely mine. I'm just the big mouth that gets the word out.:arrgh!:

[sckallst]

All these attacks can be set up in their entirety a half hour before you want to shoot. Then you maneuver your boat into position and shoot at your leisure. There is no hurried mashing of information into the TDC before everything goes stale. When it's time to shoot you have nothing to do but mash the button at appropriate times and sip your mai tai.



That, to me, is the real beauty of this. If you play like "real life" and don't time compress yourself to the gratification of firing off the fish and then wait couple of minutes for the payoff, you can really come to appreciate the approach phase of the attack. You compile good target data and set yourself up so you don't have to drive like a drunken sailor at flank speed to get off your fish. So long as the target doesn't change course on you, and your numbers are good, you can make your attack whenever and wherever you want along the track, using the prefigured analysis.

It just makes the attack seem so much more 'professional'. You can spend your time on your final approach making sure the doors are open and the fish are set just how you want them and checking off all the little things that sometimes get forgotten when things aren't prepared. You can even use that extra time trying to be real fancy by setting up an attack on a second target, or paying more attention to what the escorts are doing. You're also just more prepared if something about the target does change, because if you really understand your situation, it should be fairly easy to figure out what, if anything, you can do to put yourself back on track to fire. Most target changes aren't going to completely invalidate your previous solution, and if you keep your vector drawing handy a new solution can often be as simple as changing one line and remeasuring one angle.

[Eddy Lawson]

Hey there, thanks for this amazing new method. I've tested it and it works "just" perfectly. Great job!

I just want to ask one thing... I was curious to try the BAAANG you talked about in the first posts of this thread. You said that sending a fish to the stern, mid and bow they are going to hit almost at the same time.
I just can't figure out how to do it because in my game merchants don't go backward easily in my game! :rotfl:
I don't think I have to turn or to mess up with the TDC so how do you do that?!

[Rockin Robbins]

It's not really easy because you DO have to mess with the TDC and give up some accuracy on shots 2 and 3. Here's the deal.

Set up as usual for your first shot. Have the periscope on the shoot bearing and shoot torpedo #1 at the stern. Then quickly jump just in front of the target, freeze and press the send range/bearing button. Send this puppy to the MOT. Jump just ahead of the boat again and press the send range/bearing button. Shoot this one at the bow.

It's vitally important that you don't move the periscope after you press the send range/bearing button, because that's where the next torpedo is going. Your angle on the bow is going to be slightly inaccurate for shot 2 and 3 (we don't have time to adjust it), but shouldn't mess up the shot. At most it will make a couple of yard difference in where the torpedo strikes the target.

Since the first torpedo you fire has to go the longest distance, they will strike at about the same time. And instead of the normal longitudinal spread where the three torpedoes advance toward the target in a single line, easily outmaneuvered if the target sees it soon enough, your divergent spread is three torpedoes taking three different tracks, side-by-side toward the target. This spread is much more difficult to avoid.

Shooting in the order stern/MOT/bow gives you the most divergent possible spread, bow/MOT/stern gives you the least divergent spread. Because of the nature of the spread you have to use the TDC. Only the first shot could be set up using vector analysis.

[AngronIsAngry]

I keep reading "enter xx into TDC" in this thread.
I have been entering nil into the TDC as the whole point of the method is the determination of a point for the torps to hit. Given I had to manually clear relics of former attacks, but that's it. Am I doing something wrong (because I'm still hitting targets)?

[Eddy Lawson]

Mmm... sounds like a decent plan to blow up things :up:
I'm on my way to try it.

Thanks RR!

[Nisgeis]

Some people like to check their solution with the TDC, but there is no need to use it if you are using a longitudinal spread by waiting for the parts you want to cross the wire. If you want to fire a diverse spread, by using the spread wheel, then you have a problem of the target moving and the aiming point (stern) is moving as well. You can use the spread wheel without using the TDC, but you'll have to be quick, as the target is moving and your torpedoes will lag behind a bit, as it will have moved on. Depending on the speed of the target, the results will vary.

You can compensate for this by pre-determining at what interval you will fire the torpedoes at and then working out how far the target will have moved and using that plus the target's length to work out your spread. To make this easy, use the TSAC (Torpedo Spread Angle Calculator). A target travelling at 1 knot will travel 100 feet in one minute, so if the target is going at 12 knots it will travel 1,200 feet per minute.

But that's all getting quite complicated. If you are firing torpedoes with the historical contraint, then you'd need to leave a gap between torpedoes, but as this is a game you don't if you don't want to. Use the TSAC to work out the target length in degrees, with the correct torpedo run length (from your drawing, it's the torpedo course up to the point where it intersects the target's track). Wait for the stern to cross the wire and then dial in the gyros until you have covered the whole ship.

Give it a try and see what happens. You may find that your torpedoes don't give full coverage, but try it and see what happens.

[Rockin Robbins]

I keep reading "enter xx into TDC" in this thread.
I have been entering nil into the TDC as the whole point of the method is the determination of a point for the torps to hit. Given I had to manually clear relics of former attacks, but that's it. Am I doing something wrong (because I'm still hitting targets)?

Angron, there are two ways to execute this attack. The first method is by entering target speed and AoB into the TDC and estimating a lead angle. The TDC computes the actual lead angle and sends the torpedo up that vector, which may be slightly different from the zero bearing angle. The difference will not impact the accuracy of your shot.

The second way is by vector analysis, which depends on having a zero value in the TDC target speed, and/or an AoB of zero or 180. (I always do both because I'm paranoid) It does not use the TDC, and since we cannot turn it off, having those values inserted is our workaround.

[AngronIsAngry]

RR you have just given me a crazy idea which might even speed up the lead angle calculation.

As the TDC lead angle deviates from the calculated one due to minor inaccuracies in setting targets AoB and speed etc. .... If you'd feed the TDC with the targets speed at a 0° bearing at an 45° angle (or whatever angle you approach), wouldn't it then calculate a lead, which you could read of the 360°bearing plotter and use for the lead of a zero gyro angle shot?

e.g. Say you have fed the TDC values as stated before and it would send your torpedo down the 8° bearing line, you would then aim your actual lead at 352° and have the torpedo go down the 0° bearing line.
Could this work? It looks good on my screen, but I don't have the bearing plotter running.

[Rockin Robbins]

That's really a great idea and I do it all the time just to make sure I have a small gyro angle. If you do it the way you describe, your next send range/bearing to TDC operation would be in a couple seconds, after you pointed the periscope at the lead angle and sent the range/bearing a second time. That will give you a perfect zero gyro shot.

The way I do it is to set up my rule of thumb lead angle for the actual attack and then go to the attack screen to see what kind of gyro angle you have, typically a couple of degrees. If you instead find a 10% gyro angle, you can be fairly sure you've done something wrong. The most common mistake would be setting low speed for the torpedo when you picked a lead angle for fast torpedos.

[I'm goin' down]

I just blew another attack using the Cromwell technique. This time my boat was off course. Here is my question. Once you have set the torpedo to run at a zero bearing in prepartion for a Cromwell attack why do you subsequently need to click the range button on the stadimeter when you move the crosshairs of the periscope to the bearing of the firing angle? It is counterintuitive.

Example. I set the stadimeter so the torpedo will intersect the target at 0 degrees. Assume the target is approaching from port at 10.9 kts. According to Old Tex's chart (screw the vertoring analysis), for a torpedo speed of 46 kts the AOB should be set at 37 degrees and the periscope aiming angle set at -8 degrees (352 degrees). We are set, except we still have to enter the range. We do this by grabbing the range handle on the stadimeter, pulling it to the right. Next, according to your instructions, we aim the periscope at 352 degree firing angle and click the range button on the stadimeter.

Why do that last step? If the torpdeo track was already set to run at 0 degrees, won't it intersect the target at 0 degrees. Clicking the range button when the periscope is aimed at 352 degrees moves the torpedo track (to port I believe). I don't understand the logic behind the last step. Enlighten me, please.

[AngronIsAngry]

It sounds like you are doing the same thing twice and differently. :hmmm:

Manually setting the torp up to swim up the 0° bearing line is vector analysis. For JPC, you feed the TDC the speed and AoB data so it sends the torp up the 0° bearing line, while your scope points at the lead angle.
Aside of the simultaneous bearing sending, sending a "fake maxed" range is possibly to amend minor data input errors, which may result in lifeboats being able to slip your torps.:ping:

[I'm goin' down]

I still do not comprehend. Do I perform the last step, or not? Rockin Robbins says the first step (setting the TDC variables to zero degrees for Speed, Range and AoB) clears the the data in the TDC. Then he instructs to input speed and AoB. Finallly, he instructs that you aim the crosshairs at the firing angle and set the range. I do not see that I have duplicated the same task, i.e. range?

[AngronIsAngry]

Method: Vector Analysis at 45° with chart
If you clear the TDC and approach at 45°, there is no reason why you input anything into the TDC afterwards, as Old-Tex's chart gives you the lead angle for this situation. So, once the TDC is clear you'd be set up and just need to point your periscope. No further data sending required.

Method: JPC
If you input speed and AoB into the TDC, you have to send the bearing at the lead angle, so the TDC sends the torp up at 0°. Doing so, there is no reason to initially clear the TDC as you override it with values anyways.
If you look at RR's 3x5 card for JPC, you'll see that clearing the TDC is not mentioned on it.

The range transmitting is actually unimportant as the range is already resolved into the lead angle, but since there is no other way to send a bearing (either for clearing the TDC or setting up the lead angle) a range value comes into play that doesn't do diddly.

[Rockin Robbins]

Actually I have to make a tiny correction about your comment on the range. The range actually cancels out of the targeting solution and does not matter at all, so long as the torpedo has the ability to travel to the impact point. Using a lead angle automatically leads more distant ships by a greater linear distance and closer targets at a smaller distance.

[Sonicfire1981]

Look, I'll read the second half of the thread soon and catch up with you guys.

Did you already notice that JPC and DOK are special cases of the Vector Analysis? Only difference is how you aquire a lead angle - via TDC or geometry. Personally I would prefer the VA, because you can easily pause the mapscreen and continue working whereas the TDC allowes no inputs while game is paused. (yes, i use the pausefunction. and i'm not ashamed to admit). also, my machine sometimes has serious losses in fps while in heavy weather or heavy convoy...

Lets see how they differ in the number of errors that may occur:
1. Target speed: vital to both, using same measurement.
2. Target track: same.
3_VA. Computing lead angle: VA uses plain geometry on a scale the captain may choose freely and while on pause. errors should be minimal.
3_JPC: basically does the reverse thing: player chooses lead angle and lets the TDC "calculate it back" to a zero-gyro-shot. To do so the player has to use the TDC twice: once setting speed and once setting AOB. I personally experienced trouble trying to get precise values. so theres two sorces for error here. The impact on the shot increase as the range increases (Remember how fast the sin-curve increases near zero).

Anyways I'm just trying to get the community to think that i am incredibly smart ;) As long as its working, everything is fine. But all this is of no use as soon as the target is aware of your present or - even worse - a DD which are all under control of Rockin Robbins. Or other drunken sailors. Or cats. who knows.
Okay, since you got me to switching autotarget off, i'm sure you have a link where my cat can read how to handle these, right? ;)

Concerning how the stern - bow attack: the most scientific way would be to aim at the stern, engage position keeper, aim middle, send bearing, fire, aim bow, send bearing, fire.

quite archaic, but very easy, rudder stb/port, 1/3 ahead and wait until wire crosses juicy parts. with a 35 AOB you gotta be quick, thou.

another solution would be to estimate how many degrees the target fills in your sights, divide by two and set the spread angle.

But you propably figured all that out already, which i didnt read because I'm busy sneaking into Tokio harbor (hate that one - anyone else?)

[Rockin Robbins]

Actually part of the beauty of all these constant bearing attacks is that you're attacking an empty spot on the water. You can set up all of these perhaps 30 minutes before you even get to the shoot location and course. So you should be able to set up any of these attacks in the TDC or without in the case of vector analysis without pausing the game no matter what the speed of your computer.

After you set up the attack you can maneuver your sub into position, wait for your target to occupy that empty spot in the water and fill him full of high explosives.

These are not Unreal Tournament III type attacks where reaction time, hand-eye coordination and agility kill your adversary. These are fishing type attacks, where you size up the situation, plan an hour ahead, set up the TDC, take fifteen minutes to maneuver into position and refine the target track, wait up to a half hour with nothing to do, leaving yourself with nothing to do but mash the button when the target finally reaches the ambush point. If you're bored during the attack, you might probably be doing it correctly.:woot:

I recommend good radio mods to keep things interesting! I personally listen to authentic period music like Pink Floyd.:rotfl:

[magic452]

RR didn't think Pink Floyd released anything on 78's

Magic

[Rockin Robbins]

RR didn't think Pink Floyd released anything on 78's

Magic

http://i196.photobucket.com/albums/aa293/RockinRobbins13/smileys/winky.gif I can't tell you everything about how I run my boat...

[Hitman]

I just watched the video tutorial, and liked the explanations -and the joking comments-, but you could have done it at night instead of that horrible weather LOL, I wasn't ever able to see the target at all in the video :haha:

Anyway, I agree with some of the previous comments in that I find it completely unnecessary and confusing to feed data into the TDC. After all, you are doing a zero GA shot, so you really don't even need to slide out the TDC and the target data tool. You could simply shoot "a la WW1" once you have calculated your lead angle (Loved the use you made of the game tools for getting it!), which BTW is the technique I use in my careers with S-Boats, as was done in real life :rock:

[I'm goin' down]

old tex made a wonderful chart that contains the torpedo speed, AOB, and lead angle for every possible Cromwell attack at a 135 degree angle. No fiddling with the tools. I have pasted on my ceiling and tatooed on my forearm. Maybe he could make one for 120 degrees (please) ? He posted a link in this thread but I do not know where it is, so you will have to find it without my assistance.

[Rockin Robbins]

Well, it's really a matter of personal preference. Inputting data into the TDC is unnecessary, but also the vector analysis is unnecessary. Each is unnecessary because the other method of executing the attack is available. Each has advantages.

The TDC method is my personal favorite because with the vector analysis method it is necessary to know the speed of your torpedo. We have 31 knot, 44 knot, 10 knot and modded torpedoes with other speeds. So with the vector analysis method you have plenty of opportunity to misremember the torpedo speed and miss by a mile. The TDC already knows your torpedo speed! And it will never remember wrongly. What's so hard about entering the speed and 45-the lead angle into the TDC? You can ALWAYS do that correctly, and the TDC remembers the hard stuff and figures out the real lead angle. With the TDC, human error is removed to a greater degree than for the vector analysis method. I'm all about mitigating human error.

The vector analysis method always gives you a perfect zero gyro shot, where in the TDC method you are estimating, so you might have a couple of degree gyro angle. This is insignificant but it bothers some people who can't stand the slightest imperfection. The vector analysis method is also not restricted to the John P Cromwell 45º attack, but can be used for an attack from any angle to the track. This makes vector analysis very versitile. Just remember, if you misremember your torpedo speed, or if you draw the triangle for a fast Mark 14 and have slow selected you miss by a mile.

The third variation is suggested by I'm goin' down. Ideally, you would have a three-dimensional chart showing all combinations of angle to the track, target speed and torpedo speed telling you the lead angle for each situation. Since we have charts on two-dimensional sheets of paper, we have to have a booklet of two-dimensional charts. I can draw the vector analysis triangle before you even find the chart. And with multiple pages containing multiple lines and colums, the possibility of error is very high. You pick the wrong page, column or row and all your torpedoes go somewhere you didn't intend.

My inclination is to teach methods that use only in-game tools, don't require you to remember torpedo speeds or information from charts, calculators, help screens, torpedo information screens or anything that is not right in front of you in the nav map, attack map or TDC display. I simplify methods to sometimes sacrifice a little bit of precision for ease of use. This loss WON'T result in any missed targets.

However, in a procedure with more complicated steps, using outside tools, the possibility for human error increases. If history tells us anything, it is that human error has a probability of 100%! If you do it right this time, you're just assuring that the errors are one time closer.

My opinion: Simplicity plus planned error equals success. Complexity plus assumption of perfect execution equals embarrassment.

[old_tex]

As requested, here are the 120 and 135 degree charts for aiming torpedoes. :up: Old_tex

http://files.filefront.com/13590544
http://files.filefront.com/13590546

[Hitman]

However, in a procedure with more complicated steps, using outside tools, the possibility for human error increases. If history tells us anything, it is that human error has a probability of 100%! If you do it right this time, you're just assuring that the errors are one time closer.


Yes, I understand your reasoning, but experience also tells me that the most important thing isn't to have or not external tools, but to practice, practice, practice....when I started manual shooting long ago I used simple and complicated methods and with both of them I only had partial success. Now, after many years of manual shooting, I am able to set up firing solutions or estimate target speed nearly "by naked eye"; practice did it, and now external tools are a pleasure to use because they make the perfect complementary part of the job (And add inmersion in the game). Of course if I was a noob, the external tools would just, as you say, add to the confusion and increase the necessary steps also raising chances of error, but the thing is with enough experience this doesn't happen, but in fact the opposite.

So I applaude your tutorials because the learning curve in this game when going for 100% realism is very hard, and your methods are the best suited for anyone who wants to learn and be confident. That said, I consider that once the confidence is there, and the player has developed his "seaman eye", going for more complicated methods and external tools adds pleasure and why not, some effectiveness. But heck, without great simplified methods and tutorials like yours, nobody would ever learn and develop the seaman eye!!!

Cheers :up:

[Munchausen]

We have 31 knot, 44 knot, 10 knot and modded torpedoes with other speeds. So with the vector analysis method you have plenty of opportunity to misremember the torpedo speed and miss by a mile.

:hmmm: For the middle one, did you mean 46 knots:06:

[Rockin Robbins]

Naw, my torpedoes all have defective motors and run slow.:haha: I TOLD you the TDC knows the torpedo speeds better than I do.:har:

[Liberatus]

file:///C:/DOCUME%7E1/DIEU-B%7E1/USTAWI%7E1/Temp/moz-screenshot.pngfile:///C:/DOCUME%7E1/DIEU-B%7E1/USTAWI%7E1/Temp/moz-screenshot-1.pnghttp://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/VectorAnalysistargeting.png

Item 5 and 6:

Can I change yards in meters?
For example:
5 knots=500 m
46 knots = 4600m
Because, I use the metric system in Silent Hunter 4

[Liberatus]

Can you help me?

[I'm goin' down]

file:///C:/DOCUME%7E1/DIEU-B%7E1/USTAWI%7E1/Temp/moz-screenshot.pngfile:///C:/DOCUME%7E1/DIEU-B%7E1/USTAWI%7E1/Temp/moz-screenshot-1.pnghttp://i196.photobucket.com/albums/aa293/RockinRobbins13/Silent%20Hunter%204/VectorAnalysistargeting.png

Item 5 and 6:

Can I change yards in meters?
For example:
5 knots=500 m
46 knots = 4600m
Because, I use the metric system in Silent Hunter 4

I am not an expert on the subject, but common sense says tell me it should work whether the conversion is to from yards to meters, miles to kilometers etc.

[Nisgeis]

Yes, it's fine to use metres. It's just a way of representing the speeds as lines, so the units don't matter.

[Liberatus]

So lead angle will be the same?
OK, Thank you for help :yeah:

[Rockin Robbins]

Yes, the angle will be the same regardless of what units you use. I'm testing it with stadia...

[Char]

My God Nisgeis,your a GENIUS!I've never been good with manual targeting,so I hit about 45% of the time.
Was Running around the Luzon Straight dodging air patrols when I did a Hydro sweep and had a tanker moving towards me on a parallel.So I set up for this "Cromwell" technique thinking "Meh,I'll give it a shot can't hurt to try." So it's holding course and moving 10 knots.I turn to get to the 45,set everything up like described and Launch 2 at her with the 3rd and 4th ready for a follow-up.and My god they hit PERFECTLY!I have never shouted so loud over a video game EVER!
One went right Amidships and the other hit just behind the bow.She kept afloat for another 5 minutes before finally giving up the ghost due to a combination of Flooding and a massive explosion in her hold.

As a man who sucks at math big time and usually misses because of it,the simplicity and the ease of this method is a Godsend!
THIS TECHNIQUE GETS MY SEIG ZEON SEAL OF APPROVAL!
http://i293.photobucket.com/albums/mm47/Blazer0079/Zeon-2.jpg

[WH4K]

I cannot make this technique work from very far out, say farther than 2000 yards. The optics are just too imprecise. A small error (0.5°) from long range can easily result in torps missing ahead of or behind the target.

That is, something seems to be screwy with the in-game optics.

For example, when I press [-] to snap the TBT to "dead ahead" (should be 0° bearing), then click the "send range/bearing" button, the resulting solution is just ever so slightly off from the 0° bearing line on the 3000-yard overlay (default feature of TMO 2.1). I don't know which one's "right." I entered a zero target speed and an arbitrary range. If I understand the TDC correctly, the AOB value shouldn't matter, as it should have no effect on the gyro angle for a stationary target.

I tried using the stern tubes and has a similar problem. Lining up the TBT on the 180° mark gives a solution that is off by a degree or two, not directly aft. I have to point the TBT almost a full degree off (looks like 180.8° or so) to get a perfectly straight aft shot.

Sure wish our fleet boats had a torpedo gyro angle indicator, like the U-boats do. Better yet, one that would indicate in fractions of a degree. 0.1° isn't much up close, but can be hundreds of feet at longer ranges.

MaxOptics IV helps somewhat in that it has a larger bearing scale than the stock game, and has marks every 1°, but it seems to not be lined up quite right.

Anyone else have these problems?

Another thing:
The text walkthrough of this technique would benefit from a clearer explanation of how to set up the TDC. If you are used to using the PK and all the other fancy stuff, it is not immediately obvious how to set up for a "dumb" 0°-gyro shot, leaving the PK out.

[I'm goin' down]

Try this: download gutted's Solution Solver program, figure out how to use it, and it will compute the lead angle for any speed or Aob. Make sure your speed measurment is accurate. :D

[Rockin Robbins]

I think what you're noticing is not a result of inaccuracy in measurement or calculation. Check this out next time: use the external camera and get close to the target. I'll bet my bippy that he saw the torpedo and made a simple 45º turn into the path, causing the torpedo to miss to the outside.

That is the major difficulty with John P Cromwell. If the target sees the approaching torpedo it's a simple matter to evade. It's very important to do this in rough water or at night. Even then you'll chock up an occasional miss.

Still, this is a great technique if only for one reason. If you miss, you've got time to set up an attack from 90º off the track. And you've shooting from ahead of escorts and less likely to be detected at this angle.

[WH4K]

I play with external camera off because I'm hardcore like that, but I take your point.

Zigzagging can also play merry hell with long-distance shots, but I don't think it will matter too much, as long as I base my calculations on the base course (the overall direction of motion) and compensate for the reduction in forward speed. Measuring the ship's speed on one leg of the zigzag, then knocking off half a knot to compensate for the evasive maneuvers, seems to be a reasonable rule of thumb.

Of course this doesn't help when the convoy does what I call a "strategic zigzag," making a large course change as a unit.

[Slyguy3129]

Oh brother tell me about the strategic zig.

A few days ago I had loaded up TMO to give OM a break and stumbled across a nice litte convoy hanging around Luzon. Dead center was a tanker of the 10,000 variety. Obviously she caught my eye and I was ready to give her my full and undivided attention. Had her primed and ready and right when I let loose, the whole convoy zags. That lady broke my heart, lucky it wasn't a total loss as one of the torpedoes hit a stray meandering about behind her and sank. Only 2800 tons though.

Eh sometimes you win sometimes lady luck takes a look and let's out a giggle.

[WH4K]

The 45° technique really does work well at night, when no one can see the torps coming.

I still get duds from time to time. Just this morning (middle of the night in game time), I had two Mk. 18 torps bounce harmlessly off a cargo ship, despite the 45° impact angle. I think next patrol I will only carry Mk. 14's. They may still be crap in 1942, but they do work slightly more often at the low-speed setting. At least I haven't had one circle back and sink me (yet).

[I'm goin' down]

The 45° technique really does work well at night, when no one can see the torps coming.

I still get duds from time to time. Just this morning (middle of the night in game time), I had two Mk. 18 torps bounce harmlessly off a cargo ship, despite the 45° impact angle. I think next patrol I will only carry Mk. 14's. They may still be crap in 1942, but they do work slightly more often at the low-speed setting. At least I haven't had one circle back and sink me (yet).

Set the torpedoes' speed at fast and the other button (the one to its right) to the right. Ducimius mentioned in a post that it helps. It is counter intuitive in the early war.:yawn:

[WH4K]

Oops, it's Mk. 23's I was thinking of. That's what I get for going on memory.

They don't have a speed setting, it's 46 kt. or nothing. Given that and their reduced range, I believe I'll go with Mk. 14's next patrol.

eta: Mk. 18's are also one speed only.

[Slyguy3129]

Yea its best to set mk14s to fast later in the war, but be warned this will increase your failure rate if you try and shoot at 90.

Fleetboat torpedoes were terrible up to 43 when they finally fixed the issues with them.

[WH4K]

It seems as if the Mk. 23 is little more than a repackaged Mk. 14. I get plenty of duds, even with impact angles well away from 90°, and regardless of exploder setting.

Supposedly, another Mk. 14 issue was that the magnetic exploder would sometimes cause premature detonations. I have not had this happen to me, so I don't know whether it's really modeled. If it is, I'd like to see "Contact" become the default exploder setting rather than "Contact/Influence."

[Rockin Robbins]

Yes, the Mark 23 is nothing but a Mark 14 with the slow speed option removed. They have the same dud rate and exploder issues. I never use Mark 14s on slow so I load up on Mark 23s every time.

There is a chance that for daytime John P Cromwell attacks Mark 18s might be an advantage. I think that Eugene Fluckey preferred Mark 14s except in calm water daytime attacks. Faster speed cancelled out the advantages of the Mark 18 and the Mark 18 was less dependable. Still the real skippers tended to take some with them for times when the torpedoes would easily be spotted otherwise.

[WH4K]

Here's a weird thing I noticed: Before mid-1943, I got duds fairly often with the Mk. 14 (and derivatives), despite using the 45° impact angle and low-speed setting. I would even get duds when using a very low impact angle, such as nearly straight-on bow or stern shots on ships at anchor.

Or is that normal? Is it supposed to still be a crapshoot, even with an impact angle nowhere near 90°?

I didn't have much luck with the magnetic exploder either. Perhaps as many as 50% of torps fired with the magnetic exploder active would detonate well before reaching the target, which I gather is more or less what happened in reality.

It's now late 1943, and the magnetic exploder seems to work perfectly. As long as I set it a foot or so under the ship's draft, BOOM, it goes off as expected.

I thought the magnetic exploders never really worked correctly, which was why Admiral Lockwood ordered their use halted? I am profiting from disobeying this order.

[Rockin Robbins]

Shhhhhhhhhhhhhh! That admiral is reputed to sometimes frequent this forum!:-?

[Giesemaschine]

Okay gents, I'm still trying to wrap my mind around this method (I haven't had too much luck) - I am also a complete NOOB to manual targeting and fleet boats in general, so bear with me.

Because this is a method using ratios, as long as I compute the correct ratio between degrees/distance (3600 yards or 46100 yards depending upon which torp. speed I use), the actual range from the target does NOT matter so long as I am:

1. Pointing exactly 45 to the target's course
2. Have my crosshairs on the lead angle (calculated by ratio above) and fire when juicy parts of ship pass by.

I'd prefer NOT to use the TDC, so with that being said, I am having some problems with a scenario I created to practice on:

Target ran 800 yards in 3 minutes, so he is doing 8 knots (correct?). At a 45 angle from 3600 yards to intersection, I measured the angle to his initial run and that is 8 degrees. So that means my lead angle (where I have to point the periscope) is at 352. Am I correct so far?

I've zeroed the AOB and Speed in the TDC, but what should I put for range? I can't zero out range in the TDC (lowest is 200) and it seems that the ranges I send to the TDC are effecting my torpedo runs, even though they shouldn't be?

I'm also placing my crosshairs dead-center on 352, but what happens is - I wait until the desired area I want to hit passes the crosshairs (let's say just under the bridge) - I fire a torpedo as the bridge passes by, but it's actually hitting way aft of the bridge, or sometimes missing altogether.

Help me out here :-?

[ColonelSandersLite]

1. Pointing exactly 45 to the target's course

I don't have time for the rest atm, but the above has nothing to do with it. What matters is a 0 gyro torpedo run. When both a target and a projectile have a constant course and speed, the lead angle does not change with distance. I know it seems counter intuitive, but it's 100% true. 45 degrees is just a part of his setup technique.

[Rockin Robbins]

That is exactly right. The reason range cancels out of the solution is that you are shooting a "straight shot" as defined by the US Navy, that is a shot with less than a 20% gyro angle. The smaller the gyro angle, the less range matters until you get to zero where range has no bearing at all on the accuracy of your shot.

Since I'm using rules of thumb and not calculations to picking a firing bearing the gyro angle is not going to be zero. It will be a small one digit number though and you will definitely hit your target.

Keep in mind that in the stock game where ships basically have no inertia, shooting a DD from ahead will usually mean that they dance out of the say of the torpedo and come after you. I'd avoid that.

But against merchies where you haven't been sighted and with ranges not exceeding 1200 yards it is pretty deadly. And if you miss you can set up for a 90º Dick O'Kane shot really quickly to snag him on the rebound.

I've found that the Cromwell attack has more of a chance of the torpedo being spotted and the ship maneuvering out of the way than a Dick O'Kane attack. It's a lot of fun with electric torpedoes. It's absolutely deadly at night.

You can modify the John P Cromwell attack to attack from any angle you wish. For instance on an attack from 50º in front, choose a shoot bearing 10º before your zero bearing, angle on the bow would be your approach angle (50º) minus your lead angle (10º in this example), so his angle on the bow would be 40º, either port or starboard depending on which side of the target you can see.

As soon as the part of the target you want to hit crosses your shoot bearing pull the trigger and that's where you will hit regardless of his range.

[SOFLCS]

Each method, be it the Cromwell, O'Kane, Sonar only, Radar only, night surface, are all tools, some specialized, some fairly broad. But in your toolbox everything flows through the TDC, it is your uniquely American advantage and incredibly versatile, as long as you give it range, aob, and speed it can track targets and let you shot anywhere your torpedoes can reach. Learn to use it by itself, not tied to any particular technique, learn about it's nuances, how to enter data, and you will have gained an amazing advantage.
Yes, 800y in 3 minutes is 8 knots. Range is not a factor when AOB and speed are zeroed, think of how the TDC works: you feed in data about an object moving in two dimensions and once it has an initial distance from you, range, the direction it's moving, aob, and how fast it's going it compiles data on where the ship will be as time passes. Now with speed zeroed AOB doesn't matter, the target isn't moving so the TDC doesn't adjust for anything. So no, it shouldn't matter. Range only applies when it's moving, and the TDC thinks the target is stationary. If the TDC thinks the target is standing still it won't calculate the collision course for the torpedoes, it will just keep it on the heading you selected through your scope/TDC.

[Rockin Robbins]

1. Pointing exactly 45 to the target's course
2. Have my crosshairs on the lead angle (calculated by ratio above) and fire when juicy parts of ship pass by.

Great so far. You're right on the money

I'd prefer NOT to use the TDC, so with that being said, I am having some problems with a scenario I created to practice on:

That's where you run astray. We DO use the TDC in our constant bearing attacks. What we don't use is the position keeper and the stadimeter. You still must enter the AOB and target speed into the TDC because it actually calculates the Torpedo Track Angle, the bearing the torpedo takes when it travels to the target. It will not be exactly zero. It will be a very small single digit number that renders range inconsequential.

Target ran 800 yards in 3 minutes, so he is doing 8 knots (correct?). At a 45 angle from 3600 yards to intersection, I measured the angle to his initial run and that is 8 degrees. So that means my lead angle (where I have to point the periscope) is at 352. Am I correct so far?

I've zeroed the AOB and Speed in the TDC, but what should I put for range? I can't zero out range in the TDC (lowest is 200) and it seems that the ranges I send to the TDC are effecting my torpedo runs, even though they shouldn't be?

Help me out here :-?

And that's your problem. You should have entered 8 knots into the TDC and pressed the send button twice.

Then you should have entered the AOB (45 minus your lead angle of 8º=37º) starboard if you're looking at the starboard side of the target or port if you're looking at its port side. Press the send button twice.

Then you have to have some non-zero range in the TDC because it goes stark raving crazy with a zero value for some reason. My video shows pulling down the range triangle to yield a range of 1300 yards or so in the TDC. Point your periscope down the shoot bearing and hold it there. Press the send button twice.

NOW you're ready to shoot as the juicy parts of the target pass the shoot bearing in your periscope. NOW you'll hit where you intended.

In this method your shoot bearing is somewhat arbitrary, being picked by rule of thumb. Your gyro angle will not be exactly zero, but its value as calculated by the TDC will be very small. We dispense with precision in exchange for results. Where there are calculations there are errors. Rules of thumb are easier to remember and then you are doing the same thing every time. Repetition brings results. The extreme error tolerance of the constant bearing technique mitigates error. We're not trying to dazzle the world with fancy mathematics and false precision, we're trying to sink ships here.:arrgh!:

Hold everything. Are you confusing the John P Cromwell technique, which uses the TDC with the Vector Analysis Technique, which doesn't? Because the Vector Analysis Technique needs speed set to zero, Angle on the Bow and range don't matter a bit (other than range has to be non-zero or the TDC goes wacko). You are setting the Torpedo Track Angle at the zero bearing and using your nav map as a vector analysis tool for the lead angle.

There are advantages and disadvantages to each. The most consequential error you can make with the vector analysis method is to do the analysis for one speed of your torpedo and shoot the other, for instance doing the lead angle analysis for a high speed torpedo then forgetting to set for high speed before you shoot. That can't happen with the John P Cromwell method because the TDC is changing your torpedo track angle automatically based on the torpedo selected. You don't even have to know the speed of your torpedo. With vector analysis that is critical. So only because of that I'd say that the John P Cromwell method is slightly more error tolerant.

[ColonelSandersLite]

Because the Vector Analysis Technique needs speed set to zero, Angle on the Bow and range don't matter a bit (other than range has to be non-zero or the TDC goes wacko). You are setting the Torpedo Track Angle at the zero bearing and using your nav map as a vector analysis tool for the lead angle.

Here's a hint for advanced users. Speed does not actually need to be zero. If speed is non zero and AOB *is* zero, and range is over like 1000 yards or whatever, this is still zero gyro in the TDC.

Why is this useful? I often attack convoys, striking 3 targets at once. Quite frequently, this involves one or two manually computed 0 gyro targets, quickly followed by one or or two targets handled by the TDC. In this situation, using the above leaves speed as one less thing I have to enter when I'm in a hurry.

[Rockin Robbins]

It is true that if AoB is zero speed cancels out. If you do it the same way all the time, though, fewer mistakes are made. So I say set both AoB and speed to zero every time you are sure to hit your mark.

Many of the details of my procedures are just error mitigation. Given that in a pressure situation errors will be made what procedures will make these errors inconsequential. Double covering options is one of those procedures. So is using the Cromwell method as opposed to vector analysis. So is arbitrarily picking a shoot bearing based on speed. It's all about error mitigation. People who love precision just HATE that. But all that counts is the BOOM at the end.

[ColonelSandersLite]

I also usually set speed to 0 as well. If for no other reason than it can be a pain to get that 0 gyro line perfectly straight using just AOB. Since speed has a hard stop at 0, it's just easier.

That being said, sometimes the time crunch in an attack means that you don't always have time to do everything you want to do. In this situation, the person who knows more of the ins and outs of targeting has the best chance of success.

[Rockin Robbins]

You must not have watched any of my videos or read any of my tutorials then. I can flatly state that with the John P Cromwell, Vector Analysis or Dick O'Kane techniques there is no time crunch. How can there be if the TDC is all set up half an hour before you shoot?:haha:

I assure you both are downright leisurely pursuits. Check out my Dick O'Kane Sonar Only Tutorial. The TDC is set up fifteen minutes before the shot. Did I say that yet another mechanism for error mitigation is to remove time pressure? All my constant bearing targeting techniques do that. No hurry, no errors. Assume there will be errors anyway and render them harmless. Simplify, toss out unnecessary calculation and steps, then do it again.

The simplest technique which can be performed in a leisurely manner leads to the most success. Time pressure is number one mother of error.

[ColonelSandersLite]

The answer to your question was two posts above. To reiterate:

I commonly find myself attacking 2 or 3 targets in a convoy simultaneously. Often the first and possibly second targets are a precalculated 0 gyro shot. The method doesn't matter matter here, there's no time crunch, use what you like (I do tables).

This is the key: The third (and sometimes second) targets are often not 0 gyro shots. In this case, if you want your 1st (target 1) 3rd (target 2) and your 5th torpedos (target 3) to all hit their targets simultaneously, there is a very substantial time crunch involved in getting everything reset to fire at the next target.

In this specific case, I find that it is very helpful to have the convoys speed with 0 AOB entered into the TDC before I launch torpedo 1.




Hmm... you know, I should really do a tutorial video on how to execute such an attack. I don't think there is actually a good one around.