Japan 1921-40: I-51, large oceanic submarine.The Type KD1 (海大型潜水艦, Kaidai-gata sensuikan) or Kaidai-I (“navy large type”, or I-51 class) was the largest Japanese submarine design, the first of a lineage that went until the KD-VII or I-76 class. This serie ran from 1921 to 1943. The very first boat of the first class was essentially it’s own class, I-51. There were two boats for the next KD-2, nine for the KD-III and so on. As the first of the Kaidai series, I-51 was also first to conduct seaplane launch and recovery trials, until struck in 1940, without combat experience. Here are the details.
Development
I-51 berthed. Best photo. From nav. hist. Cmd.
The Kaichū Type built immediately after WWI was a double-hulled medium-sized submarine, but the IJN lacked a proper, large oceanic type. This is why the KD or Kaidai type was for. It was aimed at range first and foremost, or a “first class” type capable of engaging US Navy targets close to their bases at Guam and Perl Harbour, from Japan, with a solid surface speed. When the genesis of the design started in 1918, it was inspired by the success of the German Navy’s U-boats in World War I, notably long-range cruiser submarines for commerce raiding. Somewhat inspired by the German “U-Kreuzer”, she was to be a large submarine intended for battle fleet operation. Japanese strategists wanted such submarine, bot for long-range reconnaissance, and in a war of attrition against an enemy fleet approaching Japan.
She was planned already in the 1918 (Taisho 7) Hachi-Roku Fleet Plan (Eight-six fleet program), authorized in fiscal year 1918 under the designation Project S22. construction only started from April 1921 at Kure Naval Arsenal. She was completed on June 20, 1924 (Taisho 13) and registered to Kure Naval District.
The first of a series of large submarines, it was designed to operate at high speeds while surfaced (23 knots) and engage enemy fleets, in concert with IJN surface squadrons. She was intended to repeatedly attack the U.S. fleet, and for this, exceed the enemy’s standard battle speed estimated when cruising at 15 knots with individual ship speed of approximately 21 knots. Because high-power diesels were not yet available at the time, she was equipped instead with four diesel engines, similar to those used in other submarine classes, with four propeller shafts, which was rare for the time. This resulted in the unusual shape of her inner hull, resembling two cylinders arranged side-by-side.
Design of the KD1 class
Hull and general design
The KD-1 type was the largest Japanese submarine ever built. Having no prior experience in such large designs, and given Japanese ties to UK since the 1902 Anglo-Japanese Alliance, Project S22 was based on the latest British K-class submarine. It was heavily modified however. Plans were approved and construction was entrusted to Kure Naval Arsenal when laid down on 6 April 1921. Standard displacement was an unprecedented 1,390 tons, for 1,500 tons partially loaded, and when submerged 2,430 tons fully loaded. For an overall length of 91.44 m (300 feet) and a beam of 8.81 m (29 feet) and draft of 4.60 m (15 feet). Design-wise, apart her preculiar pressure hull looking like a twin tube aft, her outer hull was shaped with a continuous deck ending in a raised prow for better seakeeping forward, streight stem, some flare, and a soft transition from the deck (which was no flat but turtle-like) to the large ballasts either side, made for a graceful, streamlined outlook. He two main telescopic antennae for her wireless radio were stored in two trench-like compartments on the port side.
She had a larger platform like extension abaft the conning tower and large loading hatches forward and aft of it and lodgings for cranes, in order to load torpedoes from the submarine itself, not counting on external help. The CT had the usual enclosed helmsman post, with windows, and a small open bridge above, in front of the fairwater surrounding the bell containing the two periscopes, watch and attack, all the way down to the pressure hull. A large platform stands behind these, quite tall over the deck. She also had a surface rudder at her stern tail. The crew amounted to 70 officers and men.
Powerplant
As said above, the intended supercharged diesels could not be obtained, so Japan opted instead for four Sulzer models, also used by other Japanese submarines. In order to attain a design speed of 23 knots (43 km/h; 26 mph) surfaced, 15 knots (28 km/h; 17 mph) submerged, engineers had to place four diesel engines, each driving its own shaft. To accommodate these, a double hull design was created, two pressure hulls joined side-by-side creating a sieways “8”. As completed however I-51 was only capable of 18.4 knots (34.1 km/h; 21.2 mph) surfaced, 8.4 knots (15.6 km/h; 9.7 mph) submerged, far for what was intended. It would be another 10 years before a Naval Academy-affiliated submarine achieved a speed of 23 knots, until the first, the Type 6A completed in 1934.
Her unrefuelled cruising range was also 20,000 nautical miles (37,000 km; 23,000 mi) at 10 knots (19 km/h; 12 mph) which was a significant increase from the 6,000 nautical miles (at 10 knots) of the submarines of the time (the Kaichu Type 3) and considered remarkable for the time. Despite these technical achievements, the I-51 design, was not regarded as a successful design, largely due to ongoing issues with her Sulzer diesel engines and so she only saw limited fleet service. Swiss Sulzer diesels were also used on French submarines, but they were considered rather as more suitable for trains and autorails than submarines. All together, these diesels developed 5,200 hp (3.9 MW), but two were removed in 1932 (and accompanying shafts). The four electric engines were rated each for 500 hp, 2,000 hp (1.5 MW) total. Submerged range was 100 nmi (190 km) at 4 knots (7.4 km/h; 4.6 mph). For such as large submarine, her diving ability was limited to 47.5 meters (156 ft).
Armament
120cm/45 Type 10 deck gun
This 12 cm/45 10th Year Type naval gun was removed in 1932. The Type 10 was initially a dual purpose anti-aircraft and coastal defense gun, derived from the 12 cm/45 3rd Year Type naval gun. It was relatively simple to produce, threw a powerful shell and did not require external power. It was also used on three cruiser classes and the Taiyō-class escort carrier.
Specs
Mass: 8.5 tons, length 5.94 m (19 ft 6 in), barrel 5.4 m (17 ft 9 in) L/45. 2.16 m (7 ft 1 in) x 2.34 m (7 ft 8 in).
Shell: Fixed QF 120×708mmR 20.6 kg (45 lb 7 oz). Semi-automatic with horizontal sliding-wedge breech, hydro-spring recoil.
Pedestal mount, rate of fire 10-12 rpm, mv 825 m/s (2,710 ft/s) range 16,000 m (17,000 yd).
Type 6 533mm Torpedo
The KD-1 type had six tubes in the bow and reloads for each, plus two in te stern and two reloads, for twenty-four of the 6th Year Type torpedo, first type using metric measurements. It was designed at the brand new Imperial Japanese Navy Technical Department, favoring a rule era naming scheme. Development started in 1914, completed in 1917 for a service in 1918 on both surface ships and submarines. Originally defined in the Eight-Eight Program replacinf the 18-in by a 21-inch caliber torpedo and planning a 61 cm (24-inch) Type 8. This went with the decision to switch to metric units. In 1922, the Washington Naval Treaty was signed by Japan and forbade any caliber besides 550 mm (French standard) and the internaitonal norm remained at 53 cm.
The 1,432 kg (3,157 lb), 6.84 m (22.4 ft) Type 6 was powered by a Wet heater to bring its 203 kg (448 lb) Shimose warhead at 7,650 m (4.13 nmi) at 36 knots (67 km/h) ot 10,000 m (5.4 nmi) at 32 kn (59 km/h), 15,000 m (8.1 nmi) at 26 knots (48 km/h). These were above average performances already compared to other Navies for that caliber.
It’s possible they tested the Type 89 in the 1930s, however the latter was only carried by the Junsen and Kaidai-type submarines. They could reach 45 knots. They could also have tested or deployed the Type 92 electric torpedo, leaving no trail (more data on latter posts).
Type 3 machine gun
Japan acquired a license and began producing Hotchkiss Mle 1897 machine guns in 6.5mm Arisaka, 87 caliber. During the Russo-Japanese War, each Japanese division had 24 Hotchkiss machine guns. Being lighter than the Russian Maxims, the Hotchkiss performed well. The production evolved to become the Type 3 Heavy Machine Gun in 1914.
Sensors
These submersibles had a pair of hydrophones, K type echo-sounder vertically only. Other equipments included a ratio transmitter special 4 and 2 receiver RDF-T4. They also had degaussine equipment with three 3/8 inch coils directly below deck and two fitted on the sail.
⚙ I-51 specifications |
|
| Displacement | 1,390 long tons (1,500 t) surfaced, 2,430 tons submerged |
| Dimensions | 91.44m x 8.81m x 4.60m |
| Propulsion | 4x Sulzer-type No.2 diesels: 5,200 bhp surfaced. 2,000 shp submerged |
| Speed | 18.4 knots () surfaced, 8.4 knots (15.6 km/h) submerged |
| Range | 508 tons fuel, 20,000 nm/10 kts surfaced, 100 nm/4 kts submerged |
| Armament | 8× 533 mm TTs (6 bow, 2 stern, 24), 1x 120 mm/45 deck gun, 2x 6.5 mm LMG AA |
| Test depth | 45.7 m (xx ft) |
| Air Group | 1 seaplane (experimentally) |
| Sensors | Hydrophones |
| Crew | 48 |
Career of the KD1 class
I-51 (1921)
As N°44 when commissioned in 1924
I-51 was laid down on 6 April 1921, launched on 29 November 1921, completed on 20 June 1924, as Submarine No. 44, and commissioned on 20 June 1924. Upon completion, she was designated the 44th Submarine, renamed I-51 Submarine shortly after completion on November 1, 1924 (Taisho 13). However, her designation underwent several revisions, including the “Naval Large Type 44”, “I-class Naval Academy Type 1”, “(First Class) Naval Academy Type 1” and finally, no designation at all. She was used exclusively as an experimental and training submarine. The experience gained from designing and building her would later serve as a starting point for the Imperial Japanese Navy’s construction of larger submarines.
On December 1, 1925 she joined I-52 into the 17th Submarine Squadron, 2nd Submarine Squadron, 2nd Fleet. She was reassigned to Kure from December 1928 to November 1935, in the Kure Defense Division from 30 November 1929 to 1 December 1930 and from 1 October 1932 to 1 January 1933. By the time, it was clear to the IJN staff through reports that she was unsuccessful in fleet service due to contant problems with her diesels, and she never returned to the fleet after SubDiv17 was reassigned to the Kure Naval District in 1928. Instead, she was retained as part of the division at the Kure Naval Arsenal just for crew training (hence her attachement to the academy) and as a test bed for new submarine technologies.
Another view from the prow
On December 10, 1928, the 17th Submarine Squadron was attached to Kure Naval District.
In 1931 she was fitted with a cylindrical seaplane hangar at Kure Arsenal, and a Yokosuka Type 2 seaplane was carried. Takeoff and landing tests were conducted and in 1933 a Kure Type 1 mod 2 catapult was fitted to the aft deck for tests, seaplane launchs were multiplied. Recovery as well. I-51 became the pioneer for aircraft-carrying IJN submarines. In May 1929, operations with a Yokosho 2-Go, a prototype for the Yokosuka E6Y floatplane, was a successful program completed by September 1931 that greenlighted the use of seaplanes for future large submarines. In 1931, her capsule-like aircraft hangar, only housing one floatplane was a parvel of engineering for the time. The seaplane could also be raised and lowered into the water by a crane. She also tested launches with the second E6Y prototype, Yokosho 2-Go Kai. Of course the installation of a catapult in 1933, making her a forerunner, proved this was the right way to go.
In addition to this experimental work, I-51 started a career of training submarine at Kure. In 1932, two diesels and associated shafts were removed; and the main deck gun, to make room for students.
On November 15, 1935 after the 17th Submarine Squadron was disbaned, she was attached directly to Kure Naval District. She continued her training duties until decommissioned and placed in the 4th Reserve on 15 December 1938. While there, she was reassigned to the Maizuru Naval District on 15 November 1939. With I-53, Naval Academy Type 2, and a Naval Academy Type 3A, she was combined to form a submarine squadron, given Kure-specific numbers and forming the 17th Submarine Squadron. She was struck from the register on April 1, 1940 and saw no combat history.
Read More/Src
Books
Conway’s all the world’s figfhting ship 1922-47.
Boyd, Carl (2012). The Japanese Submarine Force in World War II. NIP
Peattie, Mark R.; Evans, David C. (1997). Kaigun: Strategy, Tactics, and Technology in the IJN 1887-1941. NIP
Jentsura, Hansgeorg (1976). Warships of the Imperial Japanese Navy, 1869-1945. NIP
Mikesh, Robert C.; Abe, Shorzoe (1990). Japanese Aircraft 1910-1941. London: Putnam.
Passingham, Malcolm (February 2000). “Les hydravions embarqués sur sous-marins” Toute l’aéronautique et son histoire FR.
Stille, Mark (2007). Imperial Japanese Navy Submarines 1941-45. Osprey.
Links
combinedfleet.com
Japanese_53_cm_torpedo
archive.navalsubleague.org
maritime.org ONI 220 on IJN subs
navypedia.org