American technology contributed to the creation of two other anti-war weapons. -very sophisticated and very useful submarines. The first was the sound buoy, a cylindrical container containing a sound detector. Its length of 115 cm and its diameter of only 10 cm meant that a patrol plane could carry several of them, which it threw back into the water at various well-marked points. The buoys, dropped with a parachute, began to function automatically and, as soon
they detected the sound of a submarine, they transmitted signals to the plane So that a weapon also interesting does not fall into the hands of the enemy, the bottom of the cylinder included a bung plugged by a not tille which dissolved slowly; the buoy; was leaking after four hours.
With a few well-placed sonobuoys it was possible to determine the position of a submarine with relative accuracy; after which the plane went on the attack with the second American invention, the Model 24 mine. Dubbed a “mine” for security reasons, it was actually a head torpedo:acoustic seeker. When she entered the water less than 1,400 m from the objective “Fido” or “Annie wanderer”, as she was nicknamed. picked up the sounds of the submarine's engine and propeller and headed towards it. In the event of a slight lack of precision in its launch, a search procedure was programmed:if no sound appeared, "Fido" began by circling in the water until it found a " track”, which she was following then.