[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.