TDC

[Patchman123]

I was watching a video on YouTube about the Silent Service and the torpedo data computer and discovered that the TDC had thing that said "Own Position." to point to your own position on the submarine. Why doesn't Silent Hunter IV have this feature. It would sure help. The problem is that in they have essentially simplified the TDC and made it vague to understand. Is there a way to make it more complex and historically accurate like it was the old days?

[Armistead]

Well, the actual non working TDC is inside the sub where you can see all the features of a real TDC if you have the moving freecam. Would be nice to have a total working TDC but it would be a complex work. Really it isn't needed. You have everything you need on the map and with contacts on all the info a skipper would have. Using the tools you can easily figure aob both ways. I'm sure several modders wish they could make it work.

Many of us use other shooting methods that don't really require the many componants of the TDC. You may be interested in the Easy AOB mod that makes the PK wheel turn with the AOB wheel. There are other mods and tools that also help.

[Frederf]

Despite the different layout and lack of the small angle (0.2° increments) auxiliary dials, the in-game TDC is really remarkably close to shown in the screenshot (which is just a texture anyway).

I think if someone was good with 3D modeling and how to configure dials, I'm sure most if not all of those TDC dials could actually be made to work, clickable and all. That's an exciting thought.

While not adjustable or shown in any way, the TDC in generating mode takes your current speed and course into consideration when evolving the solution. So unless you miss the errors and fiddling with extra dials (which would be tasked to an officer anyway) there's not really anything to miss with those.

The time dial must be a glorified stopwatch for the TDC.

The only dial that confuses me is the is the target length dial which might have been tied to the stadimeter for AOB calculations? That or it somehow was used when generating spread angles.

What I really need to make TDC operation realistic isn't that gauge area to be modeled in historic detail, but 3-5 other people playing the game with me huddled in a phone booth shouting numbers and turning dials.

[Rockin Robbins]

Now I'm mystified. There's no "own position" anywhere! Own course came from automatic input from the compass. Own speed, similarly came from the knot meter. We have that. Otherwise the TDC could not work at all!

Its function is to calculate torpedo paths based on the relative motions of own ship and target. If it did not have the function you desire, although you are confused as to what the function is, you could hit nothing with a torpedo.

Actually, that's wrong, because with the vector analysis method, we can use the TDC as a several hundred pound paperweight. By choosing special attack parameters (any own course and speed, any target course and speed) we don't need the TDC at all.

It is reduced to a luxury, allowing us a variety of deadly attack methods and a vast flexibility to meet the requirements of our attack situations.

[Frederf]

That's not all that true. The TDC would work just fine as a solver without the ownship data input, just the solution would require a stationary ownship and/or would simply be only accurate for an instant like the german TDC.

[tomoose]

I thought one of the two dials in the working TDC represented "own ship"? It certainly looks like the same kind of dial as represented in the photo here showing "own ship". My brain hurts.

[Rockin Robbins]

That's a very strange definition for "just fine." A submerged submarine cannot function without moving, especially if it is altering its buoyancy radically by firing torpedoes. Having a solution that is only momentarily valid is also not "just fine."

Since you can do constant bearing attacks without using the TDC at all, and the above defined "just fine" TDC gives you no advantage over the constant bearing attacks, "just fine" is extended to a submarine with no TDC at all!

A TDC is on a submarine to provide additional alternatives which would not be available without it. Tracking your boat's motion opens up a whole constellation of possibilities for sinking targets which might remain untouched otherwise. The position keeper, able to predict future positions of the target without future observations does even more to extend the deadliness of the American submarine. Not having those capabilities is not "just fine."

By the way, the German TDC had the same automatic input for ownship course. Otherwise it could not calculate a gyro angle at all. After all, gyro angle is calculated from your heading. No heading info--no gyro angle. You cannot escape that requirement.

[Rockin Robbins]

Originally Posted by tomoose

I thought one of the two dials in the working TDC represented "own ship"? It certainly looks like the same kind of dial as represented in the photo here showing "own ship". My brain hurts.

Tomoose, the OP said the TDC had some kind of dial for "ownship position." That doesn't exist. What does exist in the real TDC are output dials for ownship course and speed.

Our TDC in the game reproduces the ownship course dial, but not the ownship speed dial. The ownship speed dial was just the reflection of the automatic input from the sub's knot gauge. To put it into the already crowded game TDC input would be redundant, because you already see the speed on your HUD.

Both of them are incorporated into the game TDC because without them the TDC's PK could not function and the TDC could not compute gyro angle. The OP is wrong, both on his stated observation and on his implied observation. Additionally, he is wrong in his conclusions from the flawed observations. The game TDC is in no way "vague" or difficult to use due to missing essential functions.

[Sailor Steve]

Originally Posted by Rockin Robbins

Tomoose, the OP said the TDC had some kind of dial for "ownship position." That doesn't exist.

The OP is wrong, both on his stated observation and on his implied observation.

He said that the real one had "Ownship Position", as observed in a video, and that the game didn't.

[Rockin Robbins]

That's what I'm saying also. THERE IS NO ownship position indicator on the real TDC, only an ownship course and an ownship speed.

The game TDC reproduces the ownship course, but not the ownship speed because to do so would only duplicate the knot meter on the HUD. The TDC ownship course is used to display the torpedo gyro angle, so it is useful. The ownship speed dial would not add any usefulness to the game TDC.

Therefore the OP is mistaken, both in his actual claims, and also assuming he was misspoken in his claim for an "ownship position" display and really meant "ownship course" and "ownship speed" he is wrong there too because both are present and used with the game TDC.

[Armistead]

Originally Posted by Rockin Robbins

That's what I'm saying also. THERE IS NO ownship position indicator on the real TDC, only an ownship course and an ownship speed.

The game TDC reproduces the ownship course, but not the ownship speed because to do so would only duplicate the knot meter on the HUD. The TDC ownship course is used to display the torpedo gyro angle, so it is useful. The ownship speed dial would not add any usefulness to the game TDC.

Therefore the OP is mistaken, both in his actual claims, and also assuming he was misspoken in his claim for an "ownship position" display and really meant "ownship course" and "ownship speed" he is wrong there too because both are present and used with the game TDC.

Makes perfect sense....

[Frederf]

That's a very strange definition for "just fine." A submerged submarine cannot function without moving, especially if it is altering its buoyancy radically by firing torpedoes. Having a solution that is only momentarily valid is also not "just fine."

Since you can do constant bearing attacks without using the TDC at all, and the above defined "just fine" TDC gives you no advantage over the constant bearing attacks, "just fine" is extended to a submarine with no TDC at all!

When I said that the TDC without PK update would be just fine as a solver, I meant exactly what I said. Shortening the bolded phrase to just fine misses the critical emphasis.

An instantaneous solution is "just fine" because while 2 seconds after the solution is not exactly correct, it is very close. One can also harness an instantaneous solution for a predicted instant in the very near future (5 seconds or so). The PK component of the TDC is not necessary for solution results that exceed the capabilities of the firing hardware and tube alignment tolerances as the Kriegsmarine would attest.

I'm also not suggesting the submarine not move during an attack, but that the assumption that the submarine is stationary mathematically is perfectly consistent with a highly accurate torpedo solution. The actual speed of the submarine is of little consequence to the solution.

You seem to have this perverse fascination with not using the TDC as if it touched you at summer camp when you were little. Having a backup solution in your shirt pocket is certainly being a responsible commander. Even the technophobia simpler-means-less-errors philosophy is admirable. However to state that the TDC without ownship input does not give advantage over the simplistic vector mathmatics is wrong at best.

The PK "solution evolving" function is a significant feature and that is not denied, but hardly 100% of the value for the whole computer. If the PK engine only failed during a patrol, one would not be plunged into the Stone Age.

By the way, the German TDC had the same automatic input for ownship course. Otherwise it could not calculate a gyro angle at all. After all, gyro angle is calculated from your heading. No heading info--no gyro angle. You cannot escape that requirement.

I don't know if the German TDC had an ownship course data input stream or not, but I can say that it does not follow that such data is required to generate a gyro angle order solution. The torpedo shot solution is entirely a relative one and is not dependent at all on the directon to Santa Claus's house. The TDC can safely assume that ownship heading is 000°R.

Of course having a magnetic compass feed into the TDC can provide all sorts of nice luxuries like setting the AOB by target's true course (enjoying that with fleet boats and EasyAOB) or adjusting the relative bearings during turns of the submarine, but they are luxuries in the end.

[Rockin Robbins]

Heck I use the TDC for over 90% of my attacks, so my perversion seems to be harmless so far. But who knows, it might yet take over my life and cost me my marriage and fortune. So far, I have it under complete control, however....

Yes, so long as you are shooting zero gyro angle shots, your speed and heading do not matter, and target speed cancels out of the solution equation as well, making a TDC which does not know your own course and speed "just fine."

Thinking out loud about possible exceptions, a nasty situation is when you've shot, the convoy splits up and a wounded target is limping away. You must follow. Much better than the 180º shot (because a course change by the target, plus the narrow aspect of the stern shot means lots of misses) is a shot that extends parallel to the target course and then turns 90º or so to impact at a near right angle to the target.

And it still works well, as if you match the speed of the target, you have an unchanging relative position and the TDC doesn't need to know your own course or speed. Your solution remains valid for quite a few minutes probably. But you can't do that shot without a TDC, no matter whether American or German.

On your second point, you know, you might just be right there. Without the PK, the German TDC really didn't NEED to know the actual courses of the target or submarine. The only limitation would be that you couldn't change course without destroying your TDC solution. In the American boat you can change course and the solution remains valid.

Deep, dark and nasty secret. With the technologically advanced American TDC/PK, although YOU can change course and speed without ruining your shot, the target can ruin the shot by changing course and/or speed because that information must be manually updated by you. Live by technology, die by technology!

I'm going to have to try it and see what happens! The attack map should show clearly what the situation is. If you change course and the gyro angle remains the same the TDC doesn't know what course you're on. If it changes to still hit the target, the TDC does know.

Just guessing here, I'll bet that's a function of the position keeper and not present in the German submarine. Good catch!

[Frederf]

I think I see the misunderstanding here and it's likely in part to my overly particular nature. I'm saying that ownship motion is not necessary to have a valid solution at the moment of firing. If, at the instant of firing, targetRange-AoB-targetSpeed are correct then the solution is correct.

The ownship motion only comes into play keeping a correct solution correct over time, which is replacing the previous solution with a newer solution. The ownship course and speed are not involved in the individual solutions themselves. I would like to highlight the distinction between a solution proper and an evolution of a solution. The former consists of a picture using (relative) target position & motion while the latter is an operation that needs (relative) motion of ownship as well as (relative) target position & motion to transform one picture into the next.

As for the German TDC, it's been a while since I've used it last so I had to remind myself. The only "update solution helper" that it has is a tie between the periscope bearing and the AOB setting which is something the American TDC doesn't do. So as periscope bearings are made the AOB updates to maintain the relative target couse using a very simple mathmatical relationship. The effect is that not only does changing ownship heading degrade the solution, so does any change in range. The German TDC (outside of constant range special cases) is a perfect example of a TDC that provides only instantaneous solutions.

I'm pretty confident that the German TDC doesn't have ownship speed and course information because such data only have 2 possible uses:
1. Continuous solution a la PK
2. Converting/duplicating all relative courses and bearings to their magnetic equivilent like the American TDC does with its inner/outer ring dials.

[Rockin Robbins]

In any event, the German TDC is just a really neat piece of machinery, and with a little ingenuity taking the place of American technology, I don't think it gives up much in the way of effectiveness.

I was showing another Subsim member how the Americans weren't the only ones who could take blind shots. Simply set up a Fast-90 and keep the blasted scope down. Fire when the sonar bearing is at the correct lead angle. Boom! A blind shot just like the high falutin' American prima donnas! Make sure the shot is set for the proper gyro angle beforehand! You want that gyro angle as small as possible to mitigate effects of sonar bearing error.

Of course, sonar bearing is not as accurate as a periscope bearing. You want to close the range as far as possible. But it's a darn sight better than popping up the scope, being seen and watching that CV do its imitation of a top fuel dragster and be at 30 knots in five seconds...