Torpedoes

by Francesco Cestra

Narrative
On June 10, 1940 the Regia Marina had a total of 1.450 torpedo launchers installed on units of all categories. There were 3.650 torpedoes available, both 533-mm and 450-mm models, for an average of over 2,5 weapons per torpedo launcher.

Nevertheless, this average was down to only 1,5 weapons per launcher on submarines and more modern surface vessels. There was, in fact, a surplus of antiquated 450-mm torpedoes but these models could only be used on older vessels, while the 533-mm models were barely available.

Before the hostilities, the Regia Marina gave a notable boost to the production of torpedoes and improved the facilities for the maintenance, tuning and storing of these weapons.

torpedo_it.jpg (11397 bytes)
Model W (Whitehead) 270/533 x 7.20
A Warhead
B Tanks
C Heater
D Stern
E Tail
1 Charge (270 Kg. of TNT)
2 Fuses
3 Compressed air tank (606 liters at 200 Kg./cmq)
4 Fresh water tank
5 Fuel (Kerosene)
6 Pressure regulator
7 Wet heater (combustion chamber)
8 Reciprocal engine
9 Shaft
10 Gyroscope
11 Guidance system sensor
12 Propellers
13 Rudder
14 Exhaust
15 Elevators
16 Fins
17 Controls
18 Speed regulator
19 Guidance sensor
20 Starter

 
In 1940, Italy had three manufacturing facilities specialized in the construction of torpedoes:
  • Silurificio Whitehead of Fiume, the oldest factory in the world, founded in 1860.
  • Silurificio Italiano in Baia, near Naples, operating since 1915.
  • Silurificio Motofides built near Livorno in 1937 as a secondary facility of the plant in Fiume.

Altogether, from June 10th, .1940 to September 9th, 1943 Italian units expended over 3,700 torpedoes, mostly of the newer type:

546 in 1940
1,185 in 1941
1,600 in l942
350 in 1943

The torpedoes in service in the Italian Navy during World War II were, as those of most other navies, of two caliber: 533,4-mm (21") and 450-mm (17,7"). A few dozen weapons of French origin, caliber 550-mm, constituted the only exception. (21,7 ") and 400-mm. (15") torpedoes were used on some French and Yugoslav units captured during the war.

Excluding a few French weapons, and about ten German torpedoes of the type «G.7e» of 553 mm received in 1942, all the torpedoes employed by the Italian units were of domestic origin.  Almost all weapons were propelled by over-heated air, with a reciprocal engine. This engine was a for-cylinder Brotherhood on the older models, a two cylinder on the W models and a two-row eight cylinder radial on the SI. Later, SI  introduced an eight-cylinder in line, and it is thought that a V-12 was also cinsidered.

In the mid 30s both Whitehead and the Silurificio Italiano succeeded in designing a 533mm torpedo capable of 50 knots over 4,000 meters, and a 450mm torpedo capable of 42 knots over 3,000 meters.

Despite these excellent results, which gave Italy world supremacy in heated air torpedoes, this technology was surpassed by pure oxygen or oxygenated mixtures. The Regia Marina decided, after several trials, to also reduce the maximum speeds respectively to 48 and 40 knots to assure greater safety and better reliability. Notwithstanding, having succeeded in bringing the air pressure up from 200 to 220 kgs./cmq, thanks to a notable improvement in construction, the Italian weapons were able to provide the following performances:

wpe1.jpg (9856 bytes)
SI 270/533 4x7.2
Aldo Fraccaroli Collection
  • 533 MMS: 4.000 MT. @ 50 knots for subs and 10.000 mt. @ 40 knots for cruisers and destroyers.
  • 450 MMS: 4.000 MT. @ 42 knots for Subs and Mas and 7.000 mt. @ 35 knots for torpedo boats.

As already mentioned, since the availability of 450 mm weapons was much higher in comparison to those of 533 mm, several units were equipped with 533 mm «reducing cages » to allow for the employment of 450 mm weapons.

The Italian torpedoes were equipped with fuses of the type "inertia pendulum", which would go off when the weapon hit against the hull of a ship (with a limit of 15 degrees and 5 knots). Such type remained the standard for almost all the duration of the conflict. Only in 1942 did Regia Marina start introducing fuses of the magnetic type «S.l.C.» produced by the Silurificio Italiano.

In the same period, Italy started employing on submarines German torpedoes type «G.7e» with magnetic fuses. This weapon did not generate a wake and was extremely efficient, but available in limited quantities.

In general, Italian torpedoes were very satisfactory and they did not have the well-known technical problems experienced by both the American and German models. As a matter of fact, the US Navy used some captured Italian torpedoes to study ways of improving their own models.
 

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, published by Conway Marittime Press
 

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