British R-class submarine

	HMS R2
Class overview
Name	R class
Builders	Chatham Dockyard, Kent (R1–R4); Pembroke, Wales (R5 & R6); Vickers, Barrow-in-Furness (R7 &R8); Armstrong, Elswick (R9 & R10); Cammell Laird, Birkenhead (R11 & R12);
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	6 × 18 in (457 mm) torpedo tubes (forward); 12 × 18 inch torpedoes;

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.^[1]

^ Carpenter, Dorr; Norman Polmar (1986). Submarines of the Imperial Japanese Navy. Naval Institute Press. p. 100.

[1] Carpenter, Dorr; Norman Polmar (1986). Submarines of the Imperial Japanese Navy. Naval Institute Press. p. 100.

[1]