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British R-class submarine

R-class submarine
HMS R2
Class overview
Name: R class
Builders:
Operators: Royal Navy
Preceded by: P class
Succeeded by: S class
Built: 1917–1918
In commission: 1918–1934
Planned: 12
Completed: 10
Cancelled: 2
General characteristics
Type: Submarine
Displacement:
  • 420 long tons (427 t) surfaced
  • 500 long tons (508 t) submerged
Length: 163 ft (50 m)
Beam: 16 ft (4.9 m)
Draught: 11 ft 6 in (3.51 m)
Propulsion:
  • 8-cylinder diesel engine, 480 hp (360 kW)
  • 2 × electric motors, 1,200 hp (890 kW) total
  • Single electric motor for low speed running
  • One shaft
Speed:
  • 9.5 knots (17.6 km/h) surfaced
  • 14 knots (26 km/h) submerged
Endurance: Submerged: 1 hour at 14 knots (26 km/h)
Complement: 2 officers and 20 ratings
Sensors and
processing systems:
Bow hydrophone array
Armament:

The R-class submarines were a class of 12 small British diesel-electric submarines built for the Royal Navy during World War I, and were forerunners of the modern attack submarine, in that they were designed specifically to attack and sink enemy submarines, their battery capacity and hull shape being optimized for underwater performance.

With a submerged speed of 14 knots (26 km/h; 16 mph), the class set an underwater speed record not broken until the experimental Japanese Submarine No.71 of 1938, which was capable of more than 21 knots (39 km/h; 24 mph) submerged.

Ordered in December 1917, the R class were designed to be faster underwater than on the surface, achieving a submerged speed of 14 knots (26 km/h; 16 mph) versus a surfaced speed of 9 knots (17 km/h; 10 mph). They were well-streamlined, having no external ballast tanks, casing, or deck gun, and a streamlined spindle-shaped hull of circular cross-section (not reproduced until the American Los Angeles class) which tapered sharply towards the stern and allowed only for a single screw. The bulbous bow contained five sensitive hydrophones and the lightened conning tower was also well-streamlined.

Thirty-five percent of the space inside the pressure hull was occupied by machinery. A single 8-cylinder 480 hp (360 kW) diesel engine was installed for surface propulsion, while high underwater speed was given by two large electric motors arranged one behind the other to drive the single propeller shaft, and powered by a 200-cell battery of the same type fitted to J-class submarines. The large battery was, however, sufficient for only about an hour at full power. In addition, the engine took a full day to charge the batteries, using half its power. Charging was therefore undertaken in harbour, using a supply of electricity from the shore or from special battery charging vessels.


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