What exactly does the gyro do?

[Laconic]

Originally Posted by Waervyn

This I still don't understand, sorry. If your torpedo's have a certain speed, they have to travel further (and thus longer) if the boat is further away right? How is it that range becomes irrelevant?

Range becomes irrelevant because, if your angle of attack is 90 degrees, then all targets in a particular line will pass your bow at the same time as long as they are in parallel formation to each other (as nearly all multiple-column convoys are). This means that if you fire your torpedoes on a solution to impact at 000 bearing from your boat they will all impact at the same time regardless of the range. The targets could be 10m or 10km away...it doesn't matter as long as their speed and course are the same, they are parallel to each other, and you are set up to attack them at a 90 degree angle. Here's a simple but very elegant animation detailing the tactic (credit to Rockin' Robbins).

The green line is the bearing the scope is pointed at (the shoot-solution for a 90 degree attack), and the blue line is the 000 course for the torpedoes. The submarine fires a torpedo as each red target crosses its wire; because of the changing perspective of the convoy, each target presents itself to that bearing at a different moment, making it possible to target them separately as they cross your bearing. The torpedoes should impact simultaneously regardless of the range due to the intercept angle of 90 degrees.



that shows the technique; I'll upload another one shortly that shows it even better (in daylight and at greater range).