TDC and Gyroangle?

[RodsAndAxes]

How am I supposed to use the Gyroangle? I watched a Youtube tutorial where it was set to 0, and he waited until the ship entered his plotted AOB to fire -- and that seemed to work fantastically. Every time that I try to mimic it the gyroangle flies in ten directions, ruining my careful AOB, speed, and range calculations, and sending torpedoes off in different directions.

[misha1967]

You don't "set" the gyro angle. The gyro angle is simply an indicator of the angle relative to the sub (or bearing) that the torpedo will travel when fired.

If TDC is off, this is the same as your bearing as seen in the scope/UZO. This is called "firing on my bearing", meaning that the torpedo will travel the exact same direction that you're looking in the scope. Works great if your target is considerate enough to not be moving.

If TDC is on, it is the bearing that the torpedo will travel based on the data you have entered into the TDC.

What the vid you were watching was probably showing was the very effective "90 degree attack" scenario, which is actually quite simple to us and makes hitting with manual TDC a breeze. As long as you're at 90 degrees to your target's course, that is.

I'll explain it briefly (warning: there is no such thing as "being brief" where I'm concerned :O: ).

To use this method you need your target's course and speed. That's it. What's better, you get both at the same time by doing the following:

1) Plot your target's position on the map.
2) Wait 3 minutes and 15 seconds (your stop watch comes in handy here).
3) Plot your target's position on the map again.

Now draw a line from point one to point two. The line will give you the target's course. That's one down. Measure the distance between the two points. This will give you the target's speed if your plots were accurate and you waited exactly 3 minutes and 15 seconds between the two plots. How? The distance in meters divided by 100 is the speed in kts. 500 meters = 5 kts and so forth.

That's the data that you need.

Now you need to plot a course that will place you at 90 degrees to the target's course (and ahead of it, of course). If your target is traveling north of you on a course of 90 degrees, your perpendicular (as it is called in trig, and I promise this is the last time I'll use that dreaded word :03: ) course will be 0 degrees. Use the protractor if need be, but it's really only a matter of taking the target's course and adding/subtracting 90 degrees until you find a course that goes at a right angle to the target.

Place your sub on that course until you're close enough to the target's "course line" that you plotted earlier that you can easily hit. Remember that your target will follow this line if you plotted its positions correctly earlier. somewhere between 700-1,500 meters is a good place to stop.

Then stop. If in a hurry, reverse a bit until speed is zero, then stop engines. You don't HAVE to be at a full stop before proceeding, as a matter of fact it doesn't matter at all, but you'll probably want to remember to order "stop" before you go further. What DOES matter is that your current course is exactly, plus minus a degree or two, perpendicular to your target's. 90 degrees again. It's important.

Now go to your periscope and aim it at a bearing of 0 degrees (straight ahead).

Turn on the TDC and unlock the data input function by pushing the little red button so it turns green.

Set the target's speed on the TDC, the speed you found earlier.

Set the target's AOB to 90 degrees port or starboard depending on which direction the target will be traveling when passing in front of you.

Now lock the data in by pressing the TDC input button so it turns red again.

NOW you get to look at the gyro angle indicator. Turn your scope in the direction of your target until it reads zero. There shouldn't be anything there yet or you'll have missed the opportunity, but once it's at exactly zero it means that anything passing over your crosshairs at the speed and course you previously entered will be right in front of you by the time the torpedo reaches it, provided that you're at 90 degrees to its course.

Open your torpedo hatches.

So all you have to do now is to wait until the target crosses into your view and enters the vertical line of your crosshairs. If your speed and course calculations were correct and if you're at exactly 90 degrees to your target's course, you'll hit exactly the spot on your target that the vertical line is on when you fire. Of course, since we're all human, you may not be spot on so it's always a good idea to aim for the middle of the target, so wait until that hits the vertical line, then fire as many torpedoes as you wish.

The biggest beauty of this method is, other than how easy it is, that the distance to target doesn't matter. You're using a special case, mathematically speaking, where you've eliminated one of the unknowns and, since I promised not to use the "t" word again, I won't go further into that.

You may say, reasonably, that if the target is twice as far away as I thought it was, won't it take my torpedo twice as long to reach it? Yes, it will, but your target will also take twice as long to get right in front of you.

What makes this REALLY beautiful is that if you are looking at a convoy, all you have to do is to wait until a ship is centered in your crosshairs (as long as you keep your gyro at zero). You can pick 'em off one by one until your tubes run dry, then get ready for evasive action. No need to enter separate data for each target.

That's why this method was so very, very popular.

Hope this helps.

[Pisces]

... How? The distance in meters divided by 1,000 is the speed in kts. 5,000 meters = 5 kts and so forth.
...
Sorry, this slight error would make a big miss. It's "divide by 100"! 500 meters is 5 kts over 3min 15sec. :up:

[Sailor Steve]

You don't "set" the gyro angle.
Why not?

In World War II a torpedo's gyro angle was set mechanically while it was in the tube.
http://maritime.org/tech/tdc.htm

[misha1967]

Sorry, this slight error would make a big miss. It's "divide by 100"! 500 meters is 5 kts over 3min 15sec. :up:

Oopsie! Sorry 'bout that! I'll fix my typo.

Why not?

I should've said "you don't need to set it". I really need to quit posting so late :03:

Thanks!

[RodsAndAxes]

Thanks for the advice. I'm going to try it out, and hopefully this solves my torpedo doldrums. :arrgh!:

[Dunkopf]

I'm sorry, but I am having a hard time following the above suggestions... Am I missing something with "turning on the TDC?" The only way I know how to do that is to tell the guy who's icon pops up when you're looking through the attack periscope to turn on the TDC. Then, when you lock a target, he says "unknown ship, bearing such such, such and such a distance, speed so and so" and all that. I don't see a red button to input the numbers myself... heck, I don't see the TDC at all... and I also don't see the gyroangle. I'm probably missing something huge. I *do* have manual aiming set in my realism settings, but I can't find that red button or gyroangle anywhere.

[TheDarkWraith]

I'm sorry, but I am having a hard time following the above suggestions... Am I missing something with "turning on the TDC?" The only way I know how to do that is to tell the guy who's icon pops up when you're looking through the attack periscope to turn on the TDC. Then, when you lock a target, he says "unknown ship, bearing such such, such and such a distance, speed so and so" and all that. I don't see a red button to input the numbers myself... heck, I don't see the TDC at all... and I also don't see the gyroangle. I'm probably missing something huge. I *do* have manual aiming set in my realism settings, but I can't find that red button or gyroangle anywhere.

You need a UI mod. The stock game does not show any TDC dials in the scope views.

[Dunkopf]

Ha ha! That would explain things, a LOT! Any recommendations on which one to use?

[thebeasle]

I like this one http://www.subsim.com/radioroom/showthread.php?t=166093

[Dunkopf]

Thank you!

[Dunkopf]

Does the torpedo speed matter for this "fast 90" attack?

[Trevally.]

Does the torpedo speed matter for this "fast 90" attack?

When you change the torp speed - you will see you gyroangle change.
Just adjust your scope until it reads zero again:up:

[Dunkopf]

Thanks.... I'm finally starting to get it now!