There have been a number of 18-inch (45cm) torpedoes in service with the Royal Navy of the United Kingdom. These have been used on ships of the Royal Navy and aircraft of both the Fleet Air Arm and Royal Air Force, while Royal Navy surface ships and submarines use 21-inch torpedoes. The British 18-inch torpedoes were 17.72 inches (45.0 cm) in diameter, beginning with the "Fiume" Whitehead torpedo of 1890.
Fiume Mark I
Purchased from Whitehead with the first delivery in 1890, and a second delivery in 1891. The weapon utilised compressed air propulsion, and was prolific for its time, having been exported to multiple other navies across the world. The decision to adopt the 18-inch torpedo calibre was made by the Admiralty in 1889, with the Fiume Mark I being the first weapon of the type, soon thereafter followed by the RGF Mark I. In 1890, Whitehead established a torpedo factory in Weymouth, chiefly for the export market - but also in order to directly supply the Royal Navy with locally-manufactured weapons. The factory initially manufactured various Fiume torpedoes, up to Mark III. Specifications: Fiume Mark I Short
Entered service: 1890 Weight: 845 lb (383 kg) Length: 11 ft 8 in (3.56 m) Explosive charge: 118.5 lb (53.8 kg) Wet guncotton Range and speed: 800 yd (730 m) at 26 kn (48 km/h) Fiume Mark I Long
Evaluation date: 1889 Weight: 1,140 lb (520 kg) Length: 16 ft 5 in (5.00 m) Explosive charge: 201 lb (91 kg) Wet guncotton Range and speed: 400 yd (370 m) at 32 kn (59 km/h), 800 yd (730 m) at 20 kn (37 km/h) Notes: Not adopted for service; acquired for testing only. Related to the Japanese Type 30.
Fiume Mark II
Purchased from Whitehead. Compressed air propulsion. The Fiume Mark II was requested by the Royal Navy Admiralty as it became available in 1893, with the condition that the weapon's top speed would be increased up to 28 knots. Whitehead resisted, but accepted with the stipulation that their upcoming Fiume Mark III would also be purchased. The torpedoes were delivered in 1894. In 1896, the Mark II was adjusted for slightly greater speed. In 1902, the Mark II* was produced, with improvements to its speed, reliability, and a less expensive steel afterbody. Specifications: Fiume Mark II
Entered service: 1894 Weight: 1,151 lb (522 kg) Length: 16 ft 8 in (5.08 m) Explosive charge: 229 lb (104 kg) Wet guncotton Range and speed: 600 yd (550 m) at 28.75 kn (53.25 km/h), 800 yd (730 m) at 27.75 kn (51.39 km/h), 1,000 yd (910 m) at 23.75 kn (43.99 km/h) Fiume Mark II*
Entered service: 1902 Weight: 1,200 lb (540 kg) (approximate) Length: 16 ft 8 in (5.08 m) Explosive charge: 229 lb (104 kg) Wet guncotton Range and speed: 1,000 yd (910 m) at 28 kn (52 km/h), 3,000 yd (2,700 m) at 15 kn (28 km/h) (approximate) Notes: Steel afterbody and improvements to valves and depth-keeping. Performance figures retrieved from the Japanese Type 32.
Fiume Mark III
Purchased from Whitehead, the final generation of Whitehead torpedoes designed at the facility in Fiume which were purchased by the Royal Navy. Developed in 1903, in production in 1904. Compressed air propulsion, progressively converted to dry heater propulsion beginning in 1909. The Fiume Mark III was the most prolific variant of Whitehead torpedoes after the turn of the century, exported worldwide; some units remained in service decades later. In 1940 a strait defence torpedo emplacement of the Oscarsborg Fortress sank the German heavy cruiser Blücher during the Battle of Drøbak Sound using multiple hits by Fiume Mark III torpedoes. Different versions of the Mark III had letter designations denoting their compatibility with various launch tube hardware and other functional properties. Among these were "SL" (side lug), "HB" (hook bracket), "SR" (short range), "LR" (long range), "VB" (foreign-specification submerged launch tubes designed by Elswick). The designation "H" was also used to denote conversion to dry heater propulsion. In 1919 it was approved to break up and scrap all remaining stocks of 18-inch Whitehead (Fiume) and Weymouth torpedoes possessed by the Royal Navy. Specifications: Fiume Mark III and Fiume Mark III HB
Entered service: 1904 Weight: 1,406 lb (638 kg) Length: 16 ft 8 in (5.08 m) Explosive charge: 205 lb (93 kg) Wet guncotton Range and speed: 1,000 yd (910 m) at 32 kn (59 km/h), 1,500 yd (1,400 m) at 28.6 kn (53.0 km/h), 2,000 yd (1,800 m) at 25.2 kn (46.7 km/h), 3,000 yd (2,700 m) at 20–21 kn (37–39 km/h) Notes: The hook bracket variant had a warhead charge of 200 lb (91 kg) and an overall weight of 1,398 lb (634 kg). Fiume Mark III* SLSR and Fiume Mark III* SLLR
Entered service: 1906 Weight: 1,398 lb (634 kg) Length: 16 ft 4 in (4.98 m) Explosive charge: 200 lb (91 kg) Wet guncotton Range and speed: 1,000 yd (910 m) at 33.5 kn (62.0 km/h), 2,000 yd (1,800 m) at 26.5 kn (49.1 km/h) (SR), 2,000 yd (1,800 m) at 24.5 kn (45.4 km/h), 3,000 yd (2,700 m) at 20 kn (37 km/h) (LR) Notes: Range and speed data for SLLR extrapolated using previous and successive figures. Fiume Mark III** SR, Fiume Mark III** LR and Fiume Mark III** VB
Entered service: 1906 Weight: 1,393 lb (632 kg) Length: 17 ft 4 in (5.28 m) Explosive charge: 200 lb (91 kg) Wet guncotton Range and speed: 1,000 yd (910 m) at 35 kn (65 km/h), 4,000 yd (3,700 m) at 22 kn (41 km/h) (SR), 2,000 yd (1,800 m) at 28.75 kn (53.25 km/h), 4,000 yd (3,700 m) at 21 kn (39 km/h) (LR), 2,000 yd (1,800 m) at 26.25 kn (48.62 km/h), 4,000 yd (3,700 m) at 19 kn (35 km/h) (VB) Notes: The SR and LR variants existed in both HB and SL versions. VB had an overall weight of 1,401 lb (635 kg). During the First World War, the VB variant was issued to HMS Gorgon (1914) and HMS Glatton (1914). Fiume Mark III** H SL and Fiume Mark III** H HB
Entered service: 1909 Weight: 1,423 lb (645 kg) (SL), 1,426 lb (647 kg) (HB) Length: 16 ft 8 in (5.08 m) Explosive charge: 200 lb (91 kg) Wet guncotton Range and speed: 3,000 yd (2,700 m) at 27.5 kn (50.9 km/h) (SL), 3,000 yd (2,700 m) at 29.5 kn (54.6 km/h) (HB) Notes: Dry heater conversions of older torpedoes, capable of a single speed setting only due to the limitations of their engines having originally been designed for compressed air. As of 1913, these weapons were allocated to HMS Shannon and HMS Cochrane.
RGF Mark I
A development of the earlier Fiume Mark I purchased from Whitehead, manufactured at the Royal Gun Factory in Woolwich. Existed in a "Short" and "Long" configuration. Manufacture began in 1891, with first deliveries taking place in 1892. Like its predecessor, the weapon utilised compressed air propulsion. Variants in service were denoted according to the launch tube hardware required for their employment, such as "SL" (side lug) or "HB" (hook bracket). Specifications: RGF Mark I Short
Entered service: 1892 Weight: 831 lb (377 kg) Length: 12 ft 4 in (3.76 m) Explosive charge: 200 lb (91 kg) Wet guncotton Range and speed: 600 yd (550 m) at 31 kn (57 km/h) RGF Mark I Long
Entered service: 1892 Weight: 1,170 lb (530 kg) Length: 16 ft 5 in (5.00 m) Explosive charge: 200 lb (91 kg) Wet guncotton Range and speed: 800 yd (730 m) at 31 kn (57 km/h)
== RGF Mark II == Developed at the Royal Gun Factory in 1893 as a lengthened version of the RGF Mark I. The Mark II had a strengthened head joint, a modified balance chamber for steadier running and was capable of a greater range of depth settings - 5 to 22 ft (1.5 to 6.7 m). By the end of the First World War in 1918, only 33 units of the RGF Mark II remained in Royal Navy stockpiles, and it was approved to break up 12 of them for scrap that year. Specifications: RGF Mark II
Entered service: 1893 Weight: 1,227 lb (557 kg) Length: 16 ft 8 in (5.08 m) Explosive charge: 188 lb (85 kg) Wet guncotton Range and speed: 800 yd (730 m) at 30.5 kn (56.5 km/h) RGF Mark II*
Entered service: 1894 Weight: 1,230 lb (560 kg) (approximate) Length: 16 ft 8 in (5.08 m) Explosive charge: 188 lb (85 kg) Wet guncotton Range and speed: 800 yd (730 m) at 30.5 kn (56.5 km/h), 1,500 yd (1,400 m) at 20.25 kn (37.50 km/h) (HB) or 1,500 yd (1,400 m) at 21.75 kn (40.28 km/h) (SL)
Weymouth Mark I
The Weymouth Mark I was the first Whitehead heated torpedo, a modification of a Fiume Mark III, first demonstrated in 1905 and put into series production the same year. Produced in the SL (side lug) variant, originally for use by torpedo boats; with the outbreak of the First World War, became reassigned to submarines due to urgent demand. Specifications: Weymouth Mark I SL
Entered service: 1905 Propulsion: Dry heater Weight: 1,493 lb (677 kg) Length: 17 ft 6 in (5.33 m) Explosive charge: 198 lb (90 kg) Wet guncotton Range and speed: 1,000 yd (910 m) at 41 kn (76 km/h), 4,000 yd (3,700 m) at 28.5 kn (52.8 km/h) Notes: The world's first heated torpedo, demonstrated in 1905 at Bincleaves to an audience of British and Japanese experts. Weymouth Mark I* SL
Entered service: 1909 Propulsion: Dry heater Weight: 1,426 lb (647 kg) Length: 17 ft 6 in (5.33 m) Explosive charge: 198 lb (90 kg) Wet guncotton or TNT Range and speed: 1,500 yd (1,400 m) at 40 kn (74 km/h), 4,000 yd (3,700 m) at 29 kn (54 km/h) Notes: Substantially improved depth-keeping mechanism and a much more reliable striker-fired contact fuze.
== Mark V == Used on the River-class and 1905 Tribal-class destroyers.
Year : about 1899 Weight : 1,353 lb (614 kg) Warhead : 296 lb (134 kg) including pistol Propulsion : Compressed air
== Mark VI == Used on destroyers of the early 1900s.
Year : about 1904 Performance : 28.5 knots (52.8 km/h; 32.8 mph) for 4,000 yd (3,700 m) or 41 knots (76 km/h; 47 mph) for 1,000 yd (910 m) Propulsion : Compressed air
== Mark VII and VII* == Introduced on the 1908 members of the Tribal class (1905) destroyers. Used by torpedo boats built before the First World War and destroyers. Used by RAF flying boats in the 1920s.
Year : 1907 Warhead : 320 lb (150 kg) TNT Performance : Mark VII :30 knots (56 km/h; 35 mph) for 6,000–7,000 yd (5,500–6,400 m)41 knots (76 km/h; 47 mph) for 3,000 yd (2,700 m) Mark VII* :29 knots (54 km/h; 33 mph) for 7,000 yd (6,400 m)35 knots (65 km/h; 40 mph) for 5,000 yd (4,600 m) Propulsion : Wet-heater
Mark VIII
Designed 1912, in service 1913. Originally developed as submarine armament. Prior to 1912, Royal Navy submarines exclusively used cold (compressed air) torpedoes, due to safety, reliability, and logistics considerations - as heated torpedoes required special launch tube hardware which facilitated ignition of the heater. It was also thought that long range was unnecessary for submarines. By 1911 these problems had been obviated, and the first heated torpedo to be launched from a Royal Navy submarine had been an 18-inch RGF Mark VII*. The Mark VIII was a successor, the first heated torpedo to be designed from the ground up to be used by British submarines. In 1917, a new variant of the Mark VIII was designated for use as an aerial torpedo; ultimately the weapon would be used in this role until the mid-1930s. During the Second World War, a total of two Mark VIII torpedoes were launched at enemy targets, both by MTBs. Specifications: RGF Mark VIII
Entered service: 1913 Propulsion: Wet heater Weight: 1,422 lb (645 kg) Length: 16 ft 8 in (5.08 m) Explosive charge: 320 lb (150 kg) TNT Range and speed: 1,500 yd (1,400 m) at 41 kn (76 km/h), 3,500 yd (3,200 m) at 29 kn (54 km/h) RGF Mark VIII*
Entered service: 1914 Propulsion: Wet heater Weight: 1,425 lb (646 kg) Length: 16 ft 8 in (5.08 m) Explosive charge: 320 lb (150 kg) TNT Range and speed: 1,500 yd (1,400 m) at 41 kn (76 km/h), 2,000 yd (1,800 m) at 39 kn (72 km/h), 3,500 yd (3,200 m) at 29 kn (54 km/h) 4,000 yd (3,700 m) at 28 kn (52 km/h)
Mark XI
Designed in 1934 and entered service in 1936. An aerial torpedo which served briefly. The design specifications called for an airdrop speed of 150 knots at an altitude of 30–100 ft (9.1–30.5 m), not to dive below 60 ft (18 m) after splashdown, and recover to its set depth within 400 yd (370 m). In service, the weapon suffered from poor durability due to the long flotation chamber. This prompted its replacement with the Mark XII. Remaining units were modified for surface vessel use and assigned to torpedo boats. During the Second World War, a mere 22 units of the Mark XI were expended. Specifications: Mark XI
Entered service: 1936 Propulsion: Burner cycle Weight: 1,500 lb (680 kg) (approximate) Length: 16 ft (4.9 m) (approximate) Explosive charge: 465 lb (211 kg) TNT Range and speed: 1,500 yd (1,400 m) at 40 kn (74 km/h), 4,000 yd (3,700 m) at 24–25 kn (44–46 km/h) Max airdrop speed: 150 kn (280 km/h) Notes: Almost entirely used for training purposes only. Superseded by the Mark XII after 1937. Mark XI Modified
Entered service: 1940 Propulsion: Burner cycle Weight: 1,500 lb (680 kg) (approximate) Length: 16 ft (4.9 m) (approximate) Explosive charge: 440 lb (200 kg) TNT Range and speed: 1,500 yd (1,400 m) at 40 kn (74 km/h), 3,000 yd (2,700 m) at 27 kn (50 km/h) Notes: Repurposed aerial torpedoes with modest modifications. Used by torpedo boats.