Thinking about the possible settings and the fixed outer 0 - 18 scale (look at the srews!) I think it workedlike this.
Turn the little white triangle to the AOB (!) - in our case 90° port.
Set speed of target - meeting the little white triangle.
Set speed of torpedo/s.
Read angle of attack and turn aircraft accordingly. (here 29 degrees to the left)
Distance is irrelevant.
(says
Pythagoras)
The torpedo/s follow/s a staight path to meet the target, no gyro turning necessary.
Edit: Hey Pisces! Nice we come to identical conclusions!