Post by Diarist on Sept 28, 2016 14:17:56 GMT 1
Hōshō (鳳翔?, literally "phoenix in flight") was the world's first commissioned ship that was designed and built as an aircraft carrier, and the first aircraft carrier of the Imperial Japanese Navy (IJN). Commissioned in 1922, the ship was used for testing carrier aircraft operations equipment, techniques, such as take-offs and landings, and carrier aircraft operational methods and tactics. The ship provided valuable lessons and experience for the IJN in early carrier air operations. Hōshō's superstructure and other obstructions to the flight deck were removed in 1924 on the advice of experienced aircrews.
Design and description
Construction of a seaplane carrier was authorized by the Japanese government in its "eight-six" fleet program of 1918. A planned sister ship, named Shokaku, was cancelled in 1922 before any construction started. Hōshō was the second warship, after the British HMS Hermes, to be designed from the keel up as an aircraft carrier, but was launched and completed earlier than Hermes.
Hōshō was planned as a seaplane carrier like the British HMS Campania with a forward flying-off deck, 32 aircraft, four low-angle 14-centimeter (5.5 in) guns, and four anti-aircraft (AA) guns. The plan was revised after reports were received from Japanese observers with the Royal Navy in Europe about the desirability to be able to land aircraft on the ship. The new requirements were modelled on HMS Furious after she received her rear flight deck in 1918. The ship was to be capable of 30 knots (56 km/h; 35 mph) and fitted with a forward flight deck, superstructure and funnels amidships, and a large hangar aft. Shortly thereafter based on observations of landing trials on Furious and HMS Argus, the world's first flush-decked aircraft carrier, Hōshō's flight deck design was revised in April 1919. The superstructure was removed and the funnels were moved to one side to create an unobstructed, full-length flight deck, and the ship was reclassified as an aircraft carrier. The ship's hull was based on that of a large cruiser and she was given a small island. Her three funnels were mounted on the starboard side and swivelled to lie horizontal during flight operations. Hōshō's designed speed was reduced to 25 knots (46 km/h; 29 mph), based on British experiences during the Great War.
General characteristics
Hōshō was completed with an overall length of 168.25 meters (552 ft 0 in). She had a beam of 17.98 meters (59 ft 0 in) and a mean draft of 6.17 meters (20 ft 3 in). The ship displaced 7,470 long tons (7,590 t) at standard load, and 9,494 long tons (9,646 t) at normal load. Her crew totalled 512 officers and men.[5] The ship was almost completely unarmoured.
Propulsion
Hōshō had two Parsons geared turbine sets with a total of 30,000 shaft horsepower (22,000 kW) driving two propeller shafts. Eight Kampon Type B water-tube boilers with a working pressure of 18.3 kg/cm2 (1,790 kPa; 260 psi) and a temperature of 138 °C (280 °F) provided steam to the turbines, although only four were oil-fired. The other four used a mix of oil and coal. The ship's designed speed was 25 knots, but she made 26.66 knots (49.37 km/h; 30.68 mph) from 31,117 shaft horsepower (23,204 kW) on her sea trials on 30 November 1922. She carried 2,700 long tons (2,700 t) of fuel oil and 940 long tons (960 t) of coal, an extraordinary total for such a small ship, to give her a range of 8,680 nautical miles (16,080 km; 9,990 mi) at 12 knots (22 km/h; 14 mph).
To reduce rolling and increase stability for aircraft operations, a gyrostabilizer produced by the American Sperry Gyroscope Company was installed. The installation initially proved unreliable as the Japanese technicians were badly trained by Sperry, but eventually the system proved its worth as the technicians gained experience.
Flight deck arrangements
Hōshō's flight deck was 168.25 meters (552 ft 0 in) long and 22.62 meters (74 ft 3 in) wide. The forward end sloped down at an angle of −5° to help aircraft accelerate during takeoff. A small island was mounted well forward on the starboard side and contained the ship's bridge and air operations control center. The island was fitted with a small tripod mast intended to mount the ship's fire-control system. Fifteen different types of landing equipment were evaluated before the British longitudinal wire system was adopted. Low landing speeds of the time meant that aircraft had little difficulty in stopping, but their light weight made them vulnerable to wind gusts that could blow them over the side of the carrier, and the longitudinal wires helped to prevent that. Forward of the island was a collapsible crane for loading aircraft into the forward hangar.
The flight deck, unlike those on Royal Navy carriers, was superimposed on the ship's hull rather than constructed as a strength deck supporting the carrier's hull structure.[6] A system of lights and mirrors along the flight deck assisted pilots in landing on the carrier.
Hōshō was the only Japanese aircraft carrier with two hangars. The forward hangar was 67.2 by 9.5 meters (220 ft 6 in by 31 ft 2 in) and only one deck in height as it was intended to house nine small aircraft, such as fighters. The two-story rear hangar measured 16.5 by 14 meters (54 ft 2 in by 45 ft 11 in) at the forward end and 29.4 by 12 meters (96 ft 5 in by 39 ft 4 in) at the rear end. It was designed to house six large aircraft, such as torpedo bombers, as well as six reserve aircraft. Each hangar was served by an aircraft elevator. The forward elevator was 10.35 by 7.86 meters (34.0 by 25.8 ft) and the aft elevator measured 13.71 by 6.34 meters (45 ft 0 in by 20 ft 10 in).
Air group
Hōshō had a normal capacity of fifteen aircraft, subject to the limitations of her hangars. She was first commissioned with an air group of nine Mitsubishi 1MF (Type 10) fighters and three to six Mitsubishi B1M3 (Type 13) torpedo bombers. In 1928, the fighters were replaced by the A1N1 (Type 3). Three years later the air group consisted of Nakajima A2N (Type 90) fighters and Mitsubishi B2M (Type 89) torpedo bombers.
Armament
Hōshō was armed with four 50-caliber 14 cm/50 3rd Year Type guns, two on each side. The two forward guns had a firing arc of 150°, including straight ahead, while the rear guns could fire 120° on either side. They fired 38-kilogram (84 lb) projectiles at a rate of six to ten rounds per minute with a muzzle velocity of about 850 m/s (2,800 ft/s); at 35°, they had a maximum range of 19,750 m (21,600 yd). A heavy gun armament was provided for Hōshō; as carrier doctrine was just evolving at this time, the impracticability of carriers engaging in gun duels had not yet been realized. Her large flight deck and lack of armor made her a vulnerable target in surface battles.
A pair of 40-caliber 8 cm/40 3rd Year Type guns on disappearing mounts provided Hōshō's only anti-aircraft defense. They were positioned on the flight deck, just forward of the rear elevator. These guns fired 5.67–5.99-kilogram (12.5–13.2 lb) projectiles at a muzzle velocity of about 680 m/s (2,231 ft/s); at 45°, this provided a maximum range of 10,800 meters (11,800 yd), and they had a maximum ceiling of 7,200 meters (23,600 ft) at 75° elevation. Their effective rate of fire was 13 to 20 rounds per minute.
Service
Early career
Hōshō's keel was laid down by the Asano Shipbuilding Company in Tsurumi-ku, Yokohama, on 16 December 1920. She was launched on 13 November 1921 and towed to Yokosuka Naval Arsenal for completion on 10 January 1922. Hōshō was delayed by repeated design changes and late deliveries of equipment, pushing the commissioning date from March to 27 December 1922. She was commissioned lacking much of her aviation equipment, and did not begin landing trials until 22 February 1923. The first landings were made by British pilots under contract, who were quickly replaced by Japanese pilots trained by the British Aviation Mission.
After Hōshō was commissioned, experienced aircrews requested changes, and the ship was modified by the Yokosuka Navy Arsenal from 6 June to 20 August 1924. The island, tripod mast, and aircraft crane were removed since they partially obstructed the flight deck and obscured pilot visibility. The forward part of the flight deck was made horizontal, and the 8 cm AA guns were moved forward, close to the position of the former island and out of the way of landing operations. After the island was removed, the carrier's flight operations were controlled from a platform extending from the side of the flight deck, a design that would be repeated in subsequent Japanese aircraft carriers. The ship was then assigned to the 1st Fleet until 15 November 1924.
Hōshō was fitted with a net used as a crash barrier aft of the forward elevator between 10 March and 2 July 1925. The barrier was intended to prevent landing aircraft from colliding with aircraft preparing to take off, and stop them from falling into the open elevator well. The barrier was hydraulically operated and could be erected in three seconds.
As the first of her kind, Hōshō provided valuable experience and insight into carrier air operations for the IJN. The ship was used for testing aircraft and equipment, particularly various types of arresting gear and optical landing aids. The lessons learned influenced the design and construction of Ryūjō and the subsequent conversions of Akagi and Kaga into aircraft carriers. Hōshō was actively used to develop carrier operational methods and tactics for the IJN during the 1920s. She was assigned to the First Carrier Division with Akagi on 1 April 1928. During the 1930s Hōshō was fitted with three different types of transverse arresting gear for trials.
Shanghai
Along with Kaga, Hōshō was assigned to the First Carrier Division and sent to China during the Shanghai Incident that began in January 1932. Operating with the Third Fleet, Hōshō arrived at the mouth of the Yangtze River on 1 February. Her aircraft participated in the IJN's first aerial combat on 5 February when three fighters, escorting two attack aircraft, were engaged by nine Chinese fighters; one Chinese fighter was damaged. Two days later, the two carriers sent some of their aircraft to Kunda Airfield where they flew ground attack missions in support of the Imperial Japanese Army. Between 23 and 26 February, Kaga and Hōshō bombers attacked Chinese airfields at Hangzhou and Suzhou, destroying a number of Chinese aircraft on the ground. On 26 February, six fighters from Hōshō, escorting nine attack aircraft from Kaga on one of the bombing raids, shot down two of five Chinese fighters that engaged them. The First Carrier Division re-joined the Combined Fleet on 20 March, after a ceasefire had been declared on 3 March.
Fourth Fleet Incident
Hōshō participated in the Combined Fleet Maneuvers of 1935 where she was attached to the IJN Fourth Fleet. The fleet was caught out in a typhoon on 23 September. The carrier and a number of other Japanese ships were badly damaged in what was referred to as the "Fourth Fleet Incident." The ship's forward flight deck collapsed and part had to be cut away before the carrier could proceed to Yokosuka for repairs. The Fourth Fleet Incident and the Tomozuru Incident of 1934, in which a top-heavy torpedo boat capsized in heavy weather, caused the Japanese command to investigate the stability of all their ships, resulting in a number of design changes to improve stability and increase hull strength.
