The pre-war issue torpedo had the disadvantage of leaving a visible trail of bubbles on the surface on its way to the target. The standard torpedo of the war suffered from early problems with its internal depth-keeping equipment, and its firing pistol, but these were solved after the Norwegian Campaign. In mid 1942 an improved version was introduced with an increased battery capacity. The increased battery capacity increased the range 50%. Falke, the first homing torpedo, was fitted with a passive acoustic homing device. It was introduced i ....