The torpedo launching equipment used on Italian ships during World War II was basically two types of both 533 mm and 450 mm.
Submarine tube with a restricting cage for smaller torpedoes.
Axial boost (the torpedo is pushed forward):
Underwater torpedo launchers, not movable and installed on submarines.
Deck mounted torpedo launchers: fixed and not installed on surface vessels, including motor torpedo boats.
Lateral boost (the torpedo is pushed laterally)
Installed on MAS, VAS and MS.
On the submarine-installed torpedo launchers the expulsion of the weapons was obtained through the introduction of compressed air. On later models, called “bubbles,” a mechanism was to capture the air, but it never functioned properly. On most Italian submarines, tubes were divided between bow and stern and were of the fixed type. On smaller submarines (called pocket subs), the torpedoes were installed in external torpedo launchers which were sealed by a cup and in which the weapon would float and leave under its own power.
Triple launcher on the Ariete
(Photo Elio Ando`)
On surface vessels the expulsion of the weapons was usually obtained through compressed air generated by a small pyrotechnic charge. These launchers were usually of the kind mounted on deck and were movable. They could have a single, double, triple or quadruple set of tubes. Some fixed models were also used, such as the 533mm ones used on motor torpedo boats (MS) which had one tube installed on each side, and similar ones installed on the “Trento” class cruisers which had four twin apparatuses installed on deck, two on each side.
Generally speaking, on surface vessels the tubes were of the following types:
Single, on some torpedo boats.
Double, on torpedo boats, older destroyers and light cruisers.
Triple, on newer destroyers, light cruisers and the torpedo boats of the “Ariete” class.
Quadruple, on the heavy cruisers and on the light cruisers of the “Capitani Romani” class.
Usually, the single tubes were installed two on each side. The double and quadruple tubes on some torpedo boats and on light cruisers were mounted one on each side, but newer destroyers and torpedo boats had them mounted centrally.
The later lateral boost launchers were powered by compressed air. This equipment, invented by Commander Masini, was very simple, light in weight and specifically suitable for use on the small and fast MAS. This installation was peculiar to the MAS and appeared on the American PT.s in 1943-44, undoubtedly a practice that had originated from the Italian design.
The equipment used by the Regia Marina was built by numerous companies, but they were generally designed by only four: Whitehead, S.I. (Silurificio Italiano), San Giorgio or Bargiacchi.
Adapted from “Le Armi delle Navi Italiane Nella Seconda Guerra Mondiale” by Erminio Bagnasco published in 1978 by Ermanno Albertelli – Parma
“Naval Weapons of WW II” by John Campbell, pupished by Conway Marittime Press