Another topic on gyro angle

[Von Due]

First, a zero degree gyro angle shot is the simplest and most accurate shot I know of. That being said:

I want to explore non zero solutions in SH3 but right now I have hit a wall of no information, information I would need to set up a non zero solution.

Let's say dead ahead is a track angle of 130 degrees on the target's course. Shooting straight ahead will make the torpedo hit at 130 degrees and that's no good for impact pistols. I therefor want a shot that will hit the target at 90 degrees so I need the gyro angle set up correctly for relative course, distance, speed, lead angle and every parameter that enters the set of equations.

One thing is how it's done in real life. Another matter entirely is how the game treats non zero shots. Is the parallax problem something to concider in SH3 (that is, the distance from your viewpoint to the torpedo tubes causes geometric complications in real life, but do they do so in the game, and in what way?) What IS the distance between the scope and tubes in the game anyway? The game provides no information that I could find.

What is the torpedo's initial run before making the turn? Does the game allow the torpedo to turn the moment it's out of the tube or does it run a predetermined distance? Turn radius. How does torp speed affect turn radius and turn rate?

All these things I would like to know but frankly, I don't know where to find this info. Been reading topics on theory and RL shots but this is a game afterall and if the designers decided to let go of reality then I'm at a complete loss.

My main question:

Is there a topic hidden somewhere that takes the reader through the GAME's theories on non zero shots, gyro angles, that will explain how the game's torpedos turn, their turn rate and radius, how to plot it prior to the shot, in short, is there a topic here that will explain everything the gamer will need to know about non zero shots?

[Mittelwaechter]

The old torpedos didn't work like that. After leaving the tube they turned accordingly to the programmed gyro angle setting and went a straight line per default. Some circle runners where only malfunctions.

Later in the war you have access to FAT and LUT torpedos. They had a second gyro component to enable them running a ladder pattern inside the convoy perimeter.

Especially the LUT version will give you some of your desired functionality, as the second gyro angle is pretty flexible. You can set the first angle leaving the tube as usual, program a straight running distance and a second turn, to let the torpedo run its ladder pattern.

The LUT has a variable ladder turning angle. I once used it as a desperate measure to sink a destroyer right above my conning tower by running the pattern directly above my U-Boot.

The zommed out TDC screen will show the running path of the LUT. I'm sure you'll find out what settings do what by checking the graphics.

Most Kaleuns don't have much experience with the FAT and LUT, as they are sunk before the technology is available.

But check Subsim for FAT and LUT and you should find more information.

[Von Due]

Perhaps I didn't make myself understood. I am not talking about pattern runs, but non zero gyro angle shots.

As I understand it, the TI and TII gyros only kicked in after an initial run of x meters, kind of like the 300 meter run before arming, OR they turned immediately after leaving the tubes.

After the initial run, the gyro setting at launch kicked in, turning the torpedo onto its terminal run (a LUT was more complex with a programmable pattern rather than a straight terminal run but I am talking about the old TI and TII).

http://www.subsim.com/radioroom/attachment.php?attachmentid=1954&stc=1&d=1462126455

That these torpedos have a gyro that will make them turn if the setting on launch is not zero, is well established. The questions here are related to how to use that turn to have the torpedo intercept the target at 90 degree AoB on impact, when the target's relative course means the track angle is not 90 degrees.

EDIT:

Even without an initial run, there is the parallax problem, that is the torpedos are not directly under the scope so the target's "bearing" as seen from the torpedo at launch is not equal to target bearing seen from the scope. Add to that the turn will need distance which further complicates the parallax problem.

[Mittelwaechter]

"That turn" is not working here. The first gyro makes the torpedo turn right after leaving the tube (as stated above).

Again -you can shoot your attached sketch with a LUT, as long as the turning point of the second gyro is within 1600 meters of the target. This is the longer leg distance of the ladder pattern. First gyro 0° - running distance your choice/problem - second gyro ~ 120° starboard.

You are fully aware of the parallax problem.

[Von Due]

Consider a spread of 3 T-I torpedos.

One going straight ahead, the two others make a turn in opposite directions at an angle determined by the gyro setting. There is no need for a LUT for a spread. As we agree, there is a turn. Whether it happens right after exiting the tube or some distance after is less important. The important things here are
- A turn takes place
- Any turn requires distance (coming from turn radius)
- This added distance adds to the parallax problem for finding the correct lead angle.

If the center torpedo is set up for a zero degree gyro angle run, and hits the target at a right angle, then the flanking torpedos will NOT hit at a right angle.

Now concider one of the flanking torpedos we just launched to be a single torpedo launched set up to hit at a right angle. This can very well be a T-I. No need for a LUT. If a LUT was needed then a T-I spread is impossible but we know it is possible, because of how the T-I gyros turn the flanking torpedos.

So I have to disagree. That turn is working, courtesy of the non zero gyro setting. Problems still remains: Figure out the turn radius, rate, lead angle, torpedo run distance.

This is what I hope to find answers to.

EDIT:
Perhaps you meant that the turn didn't happen after an initial run, in which case I will say you may be perfectly correct. There is an added distance still there though or else that torpedo made a zero radius turn which is impossible.

EDIT 2
Manually set the TDC for any valid target speed, any AoB not 0 or 180, any valid lead angle and any valid distance, then look at the W.O.'s map showing the projected path of the torpedo.

For any such path there are always 2 courses for the target so that the torpedo will hit at a right angle.

Now how to reverse engineer that one from knowing the target course and speed to getting the correct lead angle.

EDIT 3
I did a test.

On the TDC, I set up
Track angle: 135 degrees.
Target speed: Zero
Torpedo track distance: 3000 meters.

Locked the TDC to update.
Turned the scope to 45 degrees lead angle and read AoB to 90 degrees.
Gyro angle set by the TDC to 46 degrees.

Looked at the W.O.'s map and saw the projected path converging with the 45 degree bearing mark at 3000m.

So far so good.

At this point I unlocked the TDC, changed target speed to 5 kts and locked the TDC.
Turned the scope until the gyro angle was 46 degrees. Lead angle was now 51.5 degrees.
Looked at the W.O. map and the projected path was again converging on the 45 degree bearing mark at 3000 meters.

Looking at the torpedo track time on the map, I plotted where the target would have to be at the moment of launch and it matches the 51.5 degree lead angle I got earlier.

Problems:
The greater the gyro angle, it seems, the more I need to add range in the TDC to match the tip of the torp track line with the bearing and range marks on the map. At 2000 meters I need to add 300-400 meters. This is a bit of a puzzle at the moment.

I set the distance to a known value but in reality it is a challenge to know what the torpedo track range will be in the upcoming (future) launch. This bit is critical.

[Mittelwaechter]

"Your message is too short..." - I love it.

I don't write the whole essay again now.

In short: you described an attack from behind the target - in your first posting (130°) as in your sketch. A T1/T2 will not move right next to the target and turn into a 90° angle of attack.

As they did it you'll have to better your position to enable the target moving into your desired 90° hit.

[Von Due]

The 130 was the track angle. From what I understand that equals the AoB if the target was on the same course but dead ahead of me. It is a theoretical AoB in a sense. So here, the target would not necessarily be in front of me, it could be abeam or behind me depending on speed and course at the time of launch.

Both the sub and the target is moving so there is no way of telling really if I am behind the target, abeam or ahead of it at the time of launch or impact, judging only by the sketch and the track angle.

Look at page 1-4
https://archive.hnsa.org/doc/attack/index.htm#platei

[Mittelwaechter]

The function of the German TDC (TZR/Torpedo Ziel Rechner) is not described in your US Torpedo Fire Control Manual.

The TDC does the math for you!

[Von Due]

The page, and that one diagram in particular was more about showing what I mean by a non zero gyro angle shot.

About the maths. The TDC is great but it has some shortcomings.

For one thing, it can not (in the game at least) prospect the torpedo track time, from launch to impact. Only a rough estimate based on the most currect range reading prior to launch, meaning it will be the range to where the target is now, not in the future when it's hit. The TDC has no idea what the range to target will be from launch to impact. That's why the game's timer is always off, sometimes by several 10s of seconds and that even when you have the AI do all the plotting for you. Only by setting the track range manually, based on plots or other calculations, can you get the actual track range and the correct time.

If it auto-updated range to target based on sub speed and course, and target speed, course and AoB, then it could possibly prospect it but as it is, it can't.

It seems the game's TDC is optimised for zero gyro angle shots, offering less help when setting up other solutions unless there are undocumented ways of using the TDC.

Here is a scenario where non zero shots are particularly interesting.

You are traveling parallell to and slightly behind a convoy. Parallell offers the benefits of staying with the moving convoy and you have to make only a small turn to move away in case the escort breaks off to search for you. Smaller turn, less time to perform the turn, more time to get away. You also get a cleaner shot on ships in the center and on the far side.

Now the only way to get those torpedos to hit is by using non zero shots.

[bstanko6]

This is all I can say about this topic!

[bstanko6]

Von Due, you are over thinking a few things.

The TDC was engineered as a computer that worked out problems like distance from periscope to torpedoes.

I think you need to look up technical specs on TDC to get the answer you want!

Now get back to sea and sink some ships!


All joking aside. If you enter correct info in the TDC, it doesn't matter, the torp will hit, you just face errors in the torp sliding off the hull, or not detonating. Your right, the TDC is bias towards zero angle shots. It's an analog system with many flaws that a zero angle corrected.

Zero angle shots were taught and practiced at academies! Even Doenitz taught classes at times about it. This is the best angle for success.

Think of it this way, your stalking a convoy for a 24 hours, you prep your boat, take your measurements, and fire your torp...

Do you really want to waste all your effort on an odd angle shot that fails you?

[Von Due]

That's the thing. This is a game and how the TDC works is really up to the game designers. For a real submarine then absolutely, the specs and navy school would teach me what I needed to know. For games it's a bit different, if the designers so choose and if the writers of the manuals so choose. Real world data only applies if the game designers applied them.

In the real world, one would work with fractions of a degree on the gyro setting. Stock game only gives you the nearest whole number, to mention one thing.

But back on topic and the original question, as this veered off a bit.

Is there a topic somewhere, or a document, on how the game works when setting up non zero shots?

[bstanko6]

http://www.subsim.com/radioroom/showthread.php?t=206381

[Von Due]

I might have found what I need. This is for SH4 but the maths and geometry should be the same for SH3.

http://www.subsim.com/radioroom/showthread.php?t=200846&page=3 Post #45.