RNTF 21 inch Mark 2 torpedo, 1915

This 21 inch (533mm) torpedo was used by the Royal Navy from 1911 through to 1918 (and beyond). Designed and built by the Royal Naval Torpedo Factory, the Mark 2 (Mark II) was operational in 1911 and was modified several time (this is the Mod 5 version, about 1915) before being superseded by 21 inch Mk 4 (Mark IV) torpedo by 1918. It is a wet - heater design with fuel being burnt in a stream of air before being cooled by a spray of water (which then boils to steam - adding to the volume of gasses delivered to the engine). The 4-cylinder Brotherhood engine was capable of being fired from a submarine’s bow torpedo tube, from Battleship side tubes or from above-water launcher mountings on smaller warships. By adjusting the fuel and air flow rates, the Mk 2 could be set to run fast (44.5 knots) to a range of 4,500 yards, or out to 18,500 yards at 19 knots.