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Old 09-29-16, 09:02 PM   #1
ColonelSandersLite
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Getting back to the topic of working the TDC, I thought I would state my own data entry procedure when using the position keeper.


Determine target course and speed via any method.

Enter speed into the TDC first.

Enter approximate AOB into the TDC.

Enter bearing and range into the TDC.

Start the position keeper.

Fine tune the AOB.

Get fresh bearing and range entered into the TDC.




If I'm not using the position keeper, my normal procedure is:

Determine target course and speed via any method.

Ensure the position keeper is off.

Set speed to either 0 or target speed depending on method of shooting.

Send range and shoot bearing to the TDC.

Set AOB to either 0 or the AOB of the target at the shoot bearing, depending on method.

Resend range and shoot bearing to the TDC just before firing to ensure that they haven't been messed up by a stadimeter reading or whatever during the approach.
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Old 09-29-16, 10:54 PM   #2
Gray Lensman
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Quote:
Originally Posted by ColonelSandersLite View Post
Getting back to the topic of working the TDC, I thought I would state my own data entry procedure when using the position keeper.


Determine target course and speed via any method.

Enter speed into the TDC first.

Enter approximate AOB into the TDC.

Enter bearing and range into the TDC.

Start the position keeper.

Fine tune the AOB.

Get fresh bearing and range entered into the TDC.




If I'm not using the position keeper, my normal procedure is:

Determine target course and speed via any method.

Ensure the position keeper is off.

Set speed to either 0 or target speed depending on method of shooting.

Send range and shoot bearing to the TDC.

Set AOB to either 0 or the AOB of the target at the shoot bearing, depending on method.

Resend range and shoot bearing to the TDC just before firing to ensure that they haven't been messed up by a stadimeter reading or whatever during the approach.
Very glad to hear directly from you.

I'm going to use your PK steps for my initial PK training.



re: not using the PK

What method allows for a 0 (zero) speed setting?

What method allows for a 0 AOB or do you mean 90 degrees AOB?

Are those "Down the throat" setup settings?

Thanks for sharing tips!
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Old 09-30-16, 12:39 AM   #3
ColonelSandersLite
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I usually use 0 speed and AOB for zero gyro shots. I just look up the bearing to aim the scope at on on a reference table. Since you have my reference materials archive, you already have the tables I use. I probably use this method 90% or more of the time when I'm just attacking a lone merchant tracked by radar.

I also have a tendency to finish off ships using just 0 gyro shots and guessing the lead angle. I usually hit. Make enough 0 gyro shots and it's not too hard to do.

Also, yes, I've done that for down the throat shots as well.
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Old 09-30-16, 04:52 AM   #4
Gray Lensman
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Quote:
Originally Posted by ColonelSandersLite View Post
I usually use 0 speed and AOB for zero gyro shots. I just look up the bearing to aim the scope at on on a reference table. Since you have my reference materials archive, you already have the tables I use. I probably use this method 90% or more of the time when I'm just attacking a lone merchant tracked by radar.

I also have a tendency to finish off ships using just 0 gyro shots and guessing the lead angle. I usually hit. Make enough 0 gyro shots and it's not too hard to do.

Also, yes, I've done that for down the throat shots as well.
To make sure I'm understanding this correctly... You're just using 0 speed and 0 AOB as a setting on the TDC to get a "straight as possible" torpedo run and using your reference charts to place the scope on the correct lead angle?

Interesting refinement if that's the case, since my constant bearing shots (no PK) always involve setting the TDC speed to target speed (not 0 unless the target is actually stopped), choosing a lead angle to fire (i.e. usually 10 slow target/15 medium target /20 fast target degrees) and setting that as my target's AOB (at point of firing). Then I scope down the same lead angle allowing the TDC to make slight gyro alterations in the final firing solution.

re: your last (no PK step)

Quote:
Resend range and shoot bearing to the TDC just before firing to ensure that they haven't been messed up by a stadimeter reading or whatever during the approach.
I usually just quickly flip over to the attack screen momentarily to ensure that the TDC setup has not changed. I used to do it your way, but every so often I would get into some sort of "locked' situation where hitting the triangle would not reset the TDC or worse, mess up an already good setup, so rather than mess with the settings last minute automatically, I check the attack screen solution first to see if it's necessary.
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Old 09-30-16, 06:45 AM   #5
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There is one thing wrong with ColonelSandersLite's instructions for using the PK, and if you followed my earlier instructions, you already know what it is.

After entering speed and AoB it is absolutely vital that the PK be on before you take your range/bearing sight. ColonelSandersLite turns on the PK after the range/bearing sight. The reason that is wrong is that after taking the sight in ColonelSandersLite's method, your artificial target is not moving. The real target is. Therefore you introduce an error in the amount of distance the target moves between when you hit the send button on the stadimeter to when you start the PK. The artificial target, which is what the sub really shoots at, will be behind the real target by that distance.

If you subsequently take another stadimeter shot, it will correct the error. But why would you use wrong procedure to introduce the error to begin with? Just turn on the PK first and you'll be bang on every time.

I used to use a chart to do lead angle. I stopped. Why? What is easier than picking the wrong column off a chart when under time pressure? NOTHING! Humans make stupid errors given the slightest opportunity, and so will you. However the TDC doesn't make that mistake. It always knows which speed of which kind of torpedo is going out the selected tube. It always is picking the correct gyro angle. That's why the Dick O'Kane method uses a rule of thumb for lead angle and lets the TDC pick the gyro angle. It works correctly every time. People don't.

Simplify. Toss out steps that introduce foreseeable error. Then do it some more. What you're left with is repeatable valid procedure.
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Old 09-30-16, 07:54 AM   #6
ColonelSandersLite
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@RR
You ninjad me. How rude! :P. Of course, it's totally my fault for staying up all night and playing video games instead of sleeping and then trying to put together a detailed and factually accurate post .

Quote:
Originally Posted by Rockin Robbins View Post
If you subsequently take another stadimeter shot, it will correct the error. But why would you use wrong procedure to introduce the error to begin with?
They both introduce error actually. Your method has the target moving from the wrong position which causes the PK to change the AOB at an incorrect rate, which results in target course error. I honestly don't see that it makes a difference either way. Since the target is closing, a second reading will be more accurate and also allow you to verify your readings so it has an intrinsic value anyways.

Quote:
Originally Posted by Rockin Robbins View Post
What is easier than picking the wrong column off a chart when under time pressure?
Bah, I almost always know my lead angles like half an hour before I actually launch a torpedo :P. More seriously, I can honestly say that I have never missed a target that way. I don't know how many firing solutions I've worked with tables, but it's probably several hundred or even more so I genuinely think it's a total non-issue.


Edit: Of course, now that I've committed those words to the interwebs, I'm sure that ol' Murphy is going to come along and make damned sure I miss my next shot due to exactly that reason...
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Old 09-30-16, 08:49 AM   #7
Rockin Robbins
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Ah yes, the incredible advantage of constant bearing technique: you set up the shot first, THEN all you have to do is maneuver your boat into position. And that frequently can take a half hour.

It sure takes the time pressure off. You're only concerned with one thing at a time with no hurry. Personally, I still say unload as much workload on the machinery as possible.

What if you print your chart on an inkjet printer and a leaking periscope seal gets the paper wet. All that beautiful color ink runs for the hills and you're looking at a blank sheet of paper. Oh, nooooooooo Mr Bill!


Yes, you're right about introducing error. However AoB error is almost always less consequential than having your aiming point behind the target. The most error free technique would be to enter speed first, AoB second, then turning on the PK just before taking the stadimeter shot. Even that will have a tiny AoB error from the delay between hitting the send AoB button and hitting the send range/bearing button. The most important thing is to have the PK on before pegging the position with the stadimeter because position and speed are the most consequential errors. A 10º difference in AoB is most often inconsequential, especially if your gyro angle is less than 20º and your angle to the track is between 70º and 120º. Part of planning an effective attack is getting in the neighborhood of 90º to the track, keeping gyro angles below 20º and shooting for a torpedo track angle of about 110º (120º for a 20 knot target. We have charts for that but they're a bit hard to comprehend). Those three factors being true, you have the most error tolerant solution possible.

Errors are inevitable. Do what you can to make them inconsequential.

Last edited by Rockin Robbins; 09-30-16 at 09:10 AM.
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Old 09-30-16, 07:23 AM   #8
ColonelSandersLite
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Quote:
Originally Posted by Gray Lensman View Post
To make sure I'm understanding this correctly... You're just using 0 speed and 0 AOB as a setting on the TDC to get a "straight as possible" torpedo run and using your reference charts to place the scope on the correct lead angle?
Yep. Not mentioned explicitly, but to be clear, when using that method you'll want to sight the periscope at bearing 0/180 and send a range. The range you send doesn't matter, you're just telling the TDC to shoot straight with this setup.


Quote:
Originally Posted by Gray Lensman View Post
(i.e. usually 10 slow target/15 medium target /20 fast target degrees) and setting that as my target's AOB (at point of firing). Then I scope down the same lead angle allowing the TDC to make slight gyro alterations in the final firing solution.
Yeah, you got that from one of Rockin Robbins right? Nothing wrong with doing it that way either. That method has a bit more built in error correction in the event you forgot your torpedo speed setting or have the periscope pointed a bit wrong or something.

My favored method above gives a straighter gyro angle, which can yield better accuracy when shooting at long range. It is also a flatly better method in the event you don't actually know target speed and course and want to just guess the lead angle and snap a shot off when target is at some arbitrary bearing because you don't want to be fiddling with dials when you're doing that.

Both are perfectly valid.




There's a third method that combines the best of both but requires you to do more work.

First, plot the target normally and determine target speed and the track angle. For example sake, we will say track angle is 60 degrees port.

Second solve the lead angle with the lookup chart. For example sake, we will say that you need to shoot when target is on bearing 10.

Third, enter the target speed into the TDC.

Fourth, enter the target AOB for where it will be when you shoot at it. In this case, 60 - 10 means 50 degrees AOB.

Fifth, point the periscope at the aiming bearing. Bearing 10 in this example.

Sixth, just before you fire (basically just before the ship starts to cross the line is what you want), use the stadimeter to get target range and bearing.

Seventh, move the periscope back to the aiming bearing and resend range. Do not move the periscope again until you are done shooting. Shoot as you would for the other constant bearing techniques.


The downside is obviously that it's more work.

The upsides? For starters, it has exactly the same level of error forgiveness as Rockin Robbins technique above and since you're not just guessing the lead angle, the gyro angle will be very straight every time if you do it correctly. That combination makes it the most accurate method of shooting that I know. Combining this method, electric torpedoes, and map contacts enabled yields an incredible amount of accuracy even out to maximum range. Not only do I hit the ship nearly every time (baring malfunctions), I hit the exact part of the ship I was aiming at nearly every time.

The other big upside is that it allows you to more quickly change targets in a convoy attack since speed is already entered. I used this method for the 0 gyro shots in the tutorial videos you mentioned specifically because of that.
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