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, 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 submerged.
Description
Ordered in December 1917, the R class were designed to be faster underwater than on the surface, achieving a submerged speed of versus a surfaced speed of. They were well-streamlined, having no external ballast tanks, casing, or deck gun, and a streamlined spindle-shaped hull of circular cross-section which tapered sharply towards the stern and allowed only for a single screw. The bulbous bow contained five sensitivehydrophones 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 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. Despite being designed for maximum underwater performance, the R-class submarines were extremely difficult to control submerged, especially at high speeds. Surfaced, they had poor seakeeping and were slow. Minor modifications were made to, the only submarine of the class to survive into the 1930s, which made it more manageable on the surface, but reduced its submerged speed to a maximum.
Armament
The R class were the first Royal Navy submarines to be fitted with six bowtorpedo tubes, number of torpedoes being considered more important than range or size of warhead carried when attacking U-boats. The torpedotubes were originally the smaller but later changed to 21 inch. As designed, one spare torpedo was allowed for, but in operation six reloads were carried in place of the senior ratings' accommodation. It was originally intended to fit a gun on the foredeck, but this was dropped due to the adverse effect it would have had on submerged speed.
Construction
R1 through R4 were ordered from Chatham, R5 and R6 from Devonport, R7 and R8 from Vickers, R9 and R10 from Armstrong, and R11 and R12 from Cammell Laird. In August 1919, with World War I over, R5 and R6 were cancelled, the rest being completed. To save time, they used H-class components.
Service
Operating out of Killybegs, Donegal, one of the class reportedly tracked and fired on a German U-Boat in October 1918, firing a full salvo of six torpedoes of which only one hit but did not detonate. All but R4 and R10 were sold for scrap in 1923. The two survivors were relegated to ASW training at Portland. Pitched against poor performing naval trawlers the trawlers were no match to the high performance of the submarines. R10 was sold in 1929, while R4 survived as a fast underwater target at Portland until 1934.
