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Cavallini:
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Propulsion Plan |
Diesel Engines |
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The “Mameli” class was powered by two Franco Tosi “S8”
eight cylinder diesel engines capable of producing 1,500 HP (1119 Kw). These
were four-stroke motors with a primary crankshaft to which were connected
the pistons; they could not be reversed (they only rotated one way). The
engines were directly connected to a four-stage air compressor which
produced air at a pressure of 70 Kg/cm2 m (995.6 psi) and which was also
used (in reverse) to start the engines. The “Settembrini” kept the same
engine configuration, but the “Archimede and “Brin” were equipped with the
new Tosi E6, a six-cylinder, two-stroke reversible 1,700 HP (1268 Kw) diesel
engine which, on the “Liuzzi” were replaced by the EG, a similar model with
about 10 extra horsepower. The various power plants did not directly
effect the surface speed of the boats, but rather their endurance. |
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The
“Settembrini” were faster than the Mameli (18 v. 17.2 knots ) and the “Brin”
were faster than the poorly conceived “Archimede” (17.47 v. 17 knots), and
finally the “Liuzzi” were technically capable of 17.8 knots. With continuous
use and the general aging of the boats, these values became hardly
achievable, especially toward the end of their operational lives. On surface
navigation, the engines were connected to the primary axels via a clutch
joint, while the axels were connected to the propeller shafts by a geared
joint. The geared joints could be disconnected from the propeller shaft and
connected to the electric motors, thus turning them into dynamos for the
production of direct current. While submerged, the clutch joints were fully
disengaged. The two diesel engines received their supply of fresh
air from an intake place above deck within the cunning tower. The intake was
protected by a large valve, which, while the boat was submerged, was sealed.
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Electric Motors |
| On the “Mameli” the two electric motors (double coaxial
armature winding) were produced by C.G.E. and capable of producing up to 550
HP (410.1 Kw) each. All subsequent models were fitted with motors produced
by Ansaldo. The motors on the “Mameli” were powered by direct current and
could be supplied with 55, 110 or 220 volts. Each motor could be run at full
speed (550 HP) for one hour, at 416 HP for three hours and at 66 HP in
continuous motion. The Ansaldo installed on the “Settembrini” could also
produce 550 HP, but those on the “Archimede” were capable of 700 HP (522 Kw),
while the “Brin” were reduced to 650 HP and the Liuzzi to 625 HP. The
difference between the various power plant solutions allowed for various
endurance at maximum speed; the “Settembrini” performed worst (7 miles at 8
knots), while the “Brin” second series performed best (10 miles at 8.6
knots).
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Batteries |
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On the “Mameli” and the “Settembrini” there were two 56 cell storage batteries. Each cell was of the type 30 M.A.S. 870-5 produced by the SGIAE of Melzo (near Milan) and weighed 750 kg (1653 lb) The total weight of all cells was 84 tons (92.59 short tons). The batteries could deliver 5,150 amps in one hour, 7,500 amps in three (2,500 amps/hour), and 11,500 amps in twenty hours (575 amps/hour). This configuration was altered on the “Archimede” and these boats were fitted with a total of 128 cells divided into two compartments. The cells were of the type “Tudor Ironclad” and could deliver 4,270 amps in one hour, and 9,350 amps in twenty hours (565.5 amps/hour). The “Brin” were fitted with 132 cells also divided into two compartments. These cells were made by Scaini and could deliver 4,650 amps in one hour, 7,950 amps in five (1,590 amps/hour), 9,050 amps in ten (905 amps/hour), and 9,700 amps in twenty hours (485 amps/hour). The “Liuzzi” received smaller cells weighing 508 Kg (1120 lb) and produced by S.G.I.A.E. Each. There were a total of 232 cells, also divided into two compartments of 116 each, and could deliver 3,200 amps in one hour, 4,750 amps in three (1,583 amps/hour), and 7,300 amps in twenty-five hours (792 amps/hour). This configuration made the “Liuzzi” improve the original underwater range of the “Mameli”, 80 miles at 4 knots, to a respectable 110 miles at the same speed. Each cell was made of multiple positive and negative plates made of lead, each with common terminals, separated by insulators. The plates were immersed in an electrolyte solution made of pure water and pure sulfuric acid with a specific gravity of 1.250 when fully charged. Each cell produced approximately two volts and was permanently wired in series. Each of the two battery groups could be operated independently or in parallel. On the “Mameli” each battery group was divided into two busses, each composed of 28 cells (28 x 2 volts = 56 volts). |
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