 Chūyō at anchor | |
| Class overview | |
|---|---|
| Name | Taiyō class |
| Operators |  Imperial Japanese Navy |
| Preceded by | None |
| Succeeded by | Kaiyō |
| Built | 1938–1941 |
| In service | 1941–1944 |
| Completed | 3 |
| Lost | 3 |
| General characteristics (as converted) | |
| Type | Escort carrier |
| Displacement |
|
| Length | 180.2 m (591 ft 4 in) (o/a) |
| Beam | 22.5 m (73 ft 10 in) |
| Draught | 7.7–8 m (25 ft 3 in – 26 ft 3 in) |
| Installed power |
|
| Propulsion |
|
| Speed | 21knots (39 km/h; 24 mph) |
| Range | 6,500 or 8,500 nmi (12,000 or 15,700 km; 7,500 or 9,800 mi) at 18 knots (33 km/h; 21 mph) |
| Complement | 747 or 850 |
| Armament |
|
| Aircraft carried | 27–30 |
TheTaiyō-class escort carrier (大鷹型航空母艦,Taiyō-gata Kōkū-bokan) was a group of threeescort carriers used by theImperial Japanese Navy (IJN) duringWorld War II. Two of the ships were built ascargo liners in the late 1930s and subsequently taken over by the IJN and converted into escort carriers, while the third ship was converted while still under construction. The first ship converted,Taiyō,[Note 1] ferried aircraft and supplies to Japanese possessions before the start of thePacific War in December 1941 and also served as atraining ship between transport missions. Once the war began she did much the same for the newly conquered areas. Hersister ship,Un'yō did much the same in 1942.Chuyō, the last of the three to be converted, only ferried aircraft between Japan and the naval base atTruk before she was sunk by an American submarine in December 1943. Her sisters sometimes had other destinations other than Truk in 1943, but it was also their primary destination until they were damaged by American submarines in late 1943 or early 1944. After finishing their repairs in 1944, the sisters combined convoy escort duties with their transport missions and often ventured as far south as Singapore.Taiyō was the first of the pair to be sunk, torpedoed by an American submarine in August, withUn'yō following her sister a month later.
These ships wereNitta Maru-class cargo liners built byMitsubishi at theirNagasakishipyard for theshipping linesNippon Yusen Kaisha (NYK) andOsaka Shosen Kaisha (OSK).Nitta Maru andYawata Maru were ordered for NYK and both were completed before the beginning of the Pacific War in December 1941. The ships were intended for service to Europe, but the start of World War II in September 1939 restricted them to the Pacific.[1]Kasuga Maru had been ordered by OSK and wasfitting out when she was acquired by the IJN in 1940 and towed toSasebo Naval Arsenal on 1 May 1941 to finish her conversion into an escort carrier.[2][Note 2] She was the first ship to be completed as hersister ships were not converted until 1942.[4]
TheNitta Maru-class ships were 17,163-gross register ton (GRT) cargo liners that had a length of 170 metres (557 ft 9 in), abeam of 22.5 metres (73 ft 10 in) and a depth of hold of 12.4 metres (40 ft 8 in). They had anet tonnage of 9,397 and a cargo capacity of 11,800 tons.[7][8] They had accommodations for 285 passengers (127 first class, 88 second and 70 third).[7] The ships were powered by two sets of gearedsteam turbines made by the shipbuilder, each driving onepropeller shaft, using steam produced by fourwater-tube boilers.[8] The turbines were rated at a total of 25,200shaft horsepower (18,800 kW)[2] that gave them an average speed of 19knots (35 km/h; 22 mph)[5] and a maximum speed of 22.2 knots (41.1 km/h; 25.5 mph).[2][Note 3]
The conversion of theTaiyō-class ships, as the former liners were now known, was fairly austere and they wereflush-decked carriers thatdisplaced 18,120 tonnes (17,830 long tons) atstandard load[10] and 20,321 tonnes (20,000 long tons) at normal load. The ships had anoverall length of 180.2 metres (591 ft 4 in), a beam of 22.5 metres (73 ft 10 in) and adraught of 7.7–8 metres (25 ft 3 in – 26 ft 3 in). As carriers they had a speed of 21 knots (39 km/h; 24 mph).[9] The uptakes for the boilers were trunked together into a downward-curvingfunnel on thestarboard side of the hullamidships.[3] The ships carried 2,290 tonnes (2,250 long tons) offuel oil that gave them a range of 6,500nautical miles (12,000 km; 7,500 mi) at a speed of 18 knots (33 km/h; 21 mph).[9][11][Note 4]Taiyō's crew numbered 747 officers andratings while her sisters had 850 officers and crewmen.[13]
Theflight deck was 172 metres (564 ft 3 in) long and 23.5 metres (77 ft) wide. The ships had a singlehangar, approximately 91.4 metres (300 ft) long, served by two centrelineaircraft lifts, each 12 by 13 metres (39.4 ft × 42.7 ft).[11]Taiyō could accommodate a total of 27 aircraft, including four spares, and her sisters had a capacity of 30 aircraft.[3] Although larger, faster and having a larger aircraft-carrying capacity than their western counterparts, these ships were unsuited to a traditional carrier role as they lackedarresting gear.[4][14]
Taiyō, as the first ship completed, had an armament of six single 45-calibre12 cm (4.7 in) 10th Year Typeanti-aircraft (AA) guns insponsons along the sides of the hull.[9] The guns had a maximum elevation of +75° which gave them a range of 16,600 metres (18,200 yd) and a ceiling of 10,000 metres (33,000 ft). They fired 20.41-kilogram (45.0 lb) projectiles at a rate at 10–11rounds per minute at amuzzle velocity of 825–830 m/s (2,710–2,720 ft/s).[15] Her light AA consisted of eightlicense-built2.5 cm (1 in) Type 96 in four twin-gun mounts, also in sponsons along the sides of the hull.[12] They fired 0.25-kilogram (8.8 oz) projectiles at a muzzle velocity of 900 m/s (3,000 ft/s); at 50°, this provided a maximum range of 7,500 metres (8,202 yd), and an effective ceiling of 5,500 metres (18,000 ft). The maximum effectiverate of fire was only between 110 and 120 rounds per minute due to the need to frequently change the fifteen-round magazines.[16]
Chūyō andUn'yō were equipped with eight more modern 40-caliber12.7 cm (5 in) Type 89dual-purpose guns in four twin mounts on sponsons along the sides of the hull.[9] They fired 23.45-kilogram (51.7 lb) projectiles at a rate between 8 and 14 rounds per minute at a muzzle velocity of 700–725 m/s (2,300–2,380 ft/s); at 45°, this provided a maximum range of 14,800 metres (16,200 yd), and a maximum ceiling of 9,400 metres (30,800 ft).[17] They also had eight 2.5 cm Type 96 AA guns likeTaiyō.[9]
In early 1943, the four twin 2.5 cm mounts were replaced by triple mounts and varying numbers of additional Type 96 guns were added.Taiyō andUn'yō received a total of 24 guns in eight triple mounts whileChūyō had a total of 22 guns plus 5 license-built13.2 mm (0.5 in) Type 93anti-aircraft machineguns.[2] The ships also received aType 13early-warning radar in a retractable installation on the flight deck at that time. The following year,Taiyō's 12 cm guns were replaced by four 12.7 cm Type 89 guns in twin mounts. In addition,Taiyō andUn'yō had their 2.5 cm guns increased to a total of 64 weapons.[18]
| Name | Kanji | Original name[19] | Laid down | Launched[13] | Commissioned (as carrier)[13] | Fate[13] |
|---|---|---|---|---|---|---|
| Chūyō | 冲鷹 | Nitta Maru | 9 May 1938[20] | 20 May 1939 | 25 November 1942 | Sunk byUSS Sailfish, 4 December 1943 |
| Un'yō | 雲鷹 | Yawata Maru | 14 December 1938[21] | 31 October 1939 | 31 May 1942 | Sunk byUSS Barb, 17 September 1944 |
| Taiyō | 大鷹 | Kasuga Maru | 6 January 1940[5] | 19 September 1940 | 2 September 1941 | Sunk byUSS Rasher, 18 August 1944 |
Nitta Maru was requisitioned by the IJN in February 1941 and was followed byYawata Maru in October. Among other tasks they were used to transportprisoners of war[22] before beginning their conversion into escort carriers in 1942. All three ships received their naval names on 31 August.[19]
Completed before the start of the Pacific War,Taiyō ferried aircraft, supplies, and personnel between Japanese bases and trained naval aviators in between transport missions.[4] On 15 July, the ship and her sisterUn'yō were assigned to theCombined Fleet. Upon receiving news of theAmerican landings on Guadalcanal on 7 August,Taiyō and thebattleshipYamato together with the2nd and3rd Fleets sailed from Japan bound forTruk on 17 August.[23]Taiyō was detached from the fleet to deliver aircraft to theMarshall Islands on 27 August and then returned to Truk. In September the ship transferred supplies and equipment from Truk to thePhilippines,Formosa andPalau; on the return voyage she was torpedoed by an Americansubmarine. After receiving emergency repairs at Truk, the ship was sent to Japan for permanent repairs in October.[6]
Her conversion andwork up completed by the end of June 1942,Un'yō made three voyages from Japan to Truk,Saipan, andRabaul between July and October. From late October to early January 1943, she ferried aircraft from Japan to the Philippines, Palau, theDutch East Indies and Truk.[24]Taiyō began transporting aircraft from Japan to Formosa and Truk at the beginning of November.[24]Chu'yō's conversion was finished in November 1942 and she spent the next year exclusively ferrying aircraft to Truk, usually in company with one or the other of her sisters.Chu'yō andTaiyō were in company on 24 September 1943 when the latter was torpedoed;Chu'yō had to tow her toYokosuka as one propeller shaft had been damaged by the torpedo hit.Chu'yō herself was torpedoed by the submarineUSS Sailfish on 4 December; the hit blew off herbow and she had to steam in reverse. The submarine torpedoed her twice more later that day and disabled her engines. The third attack finally caused hercapsize with heavy losses.[25]
AfterTaiyō's repairs were completed in November 1943, she was transferred to the Grand Escort Command and began a refit that lasted until April 1944.[6]Un'yō was also transferred to the Grand Escort Command in December 1943, but she continued her ferry missions to Truk. While returning from one, the ship was torpedoed in the bow on 19 January 1944, causing it to sag. While en route to Japan, part of her bow broke off in a storm and caused the forward end of the flight deck to collapse. She had to steam stern-first to Yokosuka for repairs that were completed at the end of June.[24]Taiyō began escorted convoys to Manila, Formosa and Singapore after her refit was completed. She was torpedoed by the submarineUSS Rasher on 10 August which caused her aftavgas tank to explode; the carrier sank about half-an-hour later with heavy casualties.[6]Un'yō was only able to escort one convoy before she was sunk. During a return voyage from Singapore on 17 September, she was torpedoed by the submarineUSS Barb. The torpedoes knocked out her steering gear and engines; a storm developed that night and caused severe flooding that caused her to sink the following morning.[24]
