I find it best to take the fleet head on. Find their turbulence trail in the water and line up parallel to it. (Do this by using page down, looking through ju88 lower windows, and zoom all the way). Once you are lined up do exactly as someone posted before. Keep speed about 180-190, and as soon as guns start firing you can release both into the bow of the ship. They can be released from this distance since your torpedos are travelling into the ship and it's coming at you, lessening distance. Hope that helps.
SpinDoc