In WWII, submarines were equipped with an analog computer called a Torpedo Data Computer (TDC). This was a device, that when given a ship's speed, the torpedo's speed, and the ships angle on the bow (which is the angle that the ship's bow makes with a line drawn from submarine to ship), and would compute the necessary lead angle that the torpedo must take into account to intercept.
lead = arcsin(ss * sin(a) / st)
If that weren't amazing enough, the TDC would automagically send the lead angle to the gyros in the warmed-up torpedos. Not bad for the '40s, huh? My applet does not implement this feature, due to lack of actual torpedos.
Here it is: (unless your browser doesn't do Java 1.1, in which case you get a great blank space)
Click here for the source directory