Editing Japanese aircraft carrier Hiryū (section)

==Design==
''Hiryū'' was one of two large carriers approved for construction under the [[2nd Naval Armaments Supplement Programme|1931–1932 Supplementary Program]]. Originally designed as the [[sister ship]] of ''Sōryū'', her design was enlarged and modified in light of the [[Tomozuru Incident|''Tomozuru'']] and [[4th Fleet (Imperial Japanese Navy)#The Fourth Fleet incident|Fourth Fleet Incidents]] in 1934–1935 that revealed many IJN ships were top-heavy, [[Stability conditions|unstable]] and structurally weak. Her [[forecastle]] was raised and her [[hull (watercraft)|hull]] strengthened. Other changes involved increasing her [[beam (nautical)|beam]], [[displacement (ship)|displacement]], and armor protection.<ref name=c6>Chesneau 1995, p. 166</ref>

The ship had a length of {{convert|227.4|m|ftin|sp=us}} [[length overall|overall]], a beam of {{convert|22.3|m|ftin|sp=us}} and a [[draft (ship)|draft]] of {{convert|7.8|m|ftin|sp=us}}. She displaced {{convert|17300|LT|t|order=flip|sp=us|lk=on}} at [[Displacement (ship)#Standard displacement|standard]] load and {{convert|20250|LT|t|order=flip|sp=us}} at normal load. Her crew consisted of 1,100 officers and enlisted men.<ref name=j5>Jentschura, Jung & Mickel, p. 47</ref>
[[File:Hiryu under construction.jpg|thumb|''Hiryu'' [[fitting out]], 20 June 1940]]

===Machinery===
''Hiryū'' was fitted with four geared [[steam turbine]] sets with a total of {{convert|153000|shp|kW|lk=on}}, each driving one [[propeller shaft (ship)|propeller shaft]] using steam provided by eight Kampon [[water-tube boiler]]s.<ref name=j5/> The turbines and boilers were the same as those used in the {{sclass|Mogami|cruiser}}s. The ship's power and slim, [[cruiser]]-type hull with a length-to-beam ratio of 10:1 gave her a speed of {{convert|34.3|kn|lk=in}}<ref>Brown 1977, pp. 18–19</ref> and made her the fastest carrier in the world at the time of her commissioning.<ref>Parshall & Tully, p. 9</ref> ''Hiryū'' carried {{convert|4400|LT|t|order=flip|sp=us}} of [[fuel oil]] which gave her a range of {{convert|10330|nmi|lk=in}} at {{convert|18|kn}}. The boiler uptakes were trunked to the ship's starboard side amidships and exhausted just below [[flight deck]] level through two [[funnel (ship)|funnel]]s curved downward.<ref name=p9>Peattie, p. 241</ref>

===Flight deck and hangars===
The carrier's {{convert|216.9|m|ftin|adj=on|sp=us}} flight deck was {{convert|88|ft|6|in|0|order=flip|sp=us}} wide and overhung her [[superstructure]] at both ends, supported by pairs of pillars.<ref name=p9/> Nine transverse [[arrestor wire]]s were installed on the flight deck that could stop a {{convert|6000|kg|lb|sp=us|adj=on}} aircraft. One group of three wires was positioned further forward to allow the ship to land aircraft over the bow, although this was never done in practice. The flight deck was only {{convert|42|ft|m|1|order=flip|sp=us}} above the [[waterline]] and the ship's designers kept this figure low by reducing the height of the hangars.<ref name=Brown18>Brown 1977, p. 18</ref> The upper hangar was {{convert|562|by|60|ft|m|1|order=flip|sp=us}} and had an approximate height of {{convert|15|ft|m|1|order=flip|sp=us}}; the lower was {{convert|467|by|60|ft|m|1|order=flip|sp=us}} and had an approximate height of {{convert|14|ft|m|1|order=flip|sp=us}}. Together they had an approximate total area of {{convert|61740|sqft|0|order=flip|sp=us}}.<ref name=p9/> This caused problems in handling aircraft because the wings of a [[Nakajima B5N]] "Kate" [[torpedo bomber]] could neither be spread nor folded in the upper hangar.<ref name=Brown19>Brown 1977, p. 19</ref>

Aircraft were transported between the hangars and the flight deck by three [[Elevator#Aircraft elevators|elevators]], the forward one abreast the island on the centerline and the other two offset to starboard.<ref name=c6/> The forward platform measured {{convert|52.5|×|42.75|ft|m|0|order=flip|sp=us}}, the middle one {{convert|42.75|×|39.3|ft|m|0|order=flip|sp=us}}, and the rear {{convert|38.7|×|42.8|ft|m|1|order=flip|sp=us}}.<ref name=p9/> They were capable of transferring aircraft weighing up to {{convert|5000|kg|lbs|sp=us}}.<ref name=Brown18/> ''Hiryū'' had a designed aircraft capacity of 64, plus nine spares.<ref name=c6/>

''Hiryū's'' island was positioned further to the rear and encroached on the width of the flight deck, unlike ''Sōryū'' whose island was mounted on a starboard-side extension that protruded beyond the side of the hull so that it did not encroach on the width of the flight deck. ''Hiryū'' was one of only two carriers ever built whose [[Glossary of nautical terms (A-L)#island|island]] was on the port side of the ship ({{ship|Japanese aircraft carrier|Akagi||2}} was the other). The port side was chosen as an experiment to see if that side was better for flight operations by moving the island away from the ship's exhaust outlets. After construction of the succeeding ''[[Shōkaku-class aircraft carrier|Shōkaku]]''-class commenced, the Naval Air Technical Department (NATD) found that the portside location of the island on ''Hiryū'' and ''Akagi'' had an adverse impact on airflow over the flight deck. Another issue identified was that the amidships position of the island shortened the available landing area, which had the potential to be problematic in the future as aircraft landing speeds increased with their growing weight. <ref>Lengerer, pp. 91, 93</ref>

===Armament===
''Hiryū''{{'}}s primary [[anti-aircraft gun|anti-aircraft]] (AA) armament consisted of six twin-gun mounts equipped with [[12.7 cm/40 Type 89 naval gun|12.7-centimeter Type 89]] [[dual-purpose gun]]s mounted on projecting [[sponson]]s, three on either side of the carrier's hull.<ref name=Brown19/> When firing at surface targets, the guns had a range of {{convert|14700|m|yd|sp=us}}; they had a maximum ceiling of {{convert|9440|m|ft|sp=us}} at their maximum elevation of +90 degrees. Their maximum rate of fire was 14 rounds a minute, but their sustained rate of fire was approximately eight rounds per minute.<ref>Campbell, pp. 192–193</ref> The ship was equipped with two Type 94 [[Fire-control system#Naval fire control|fire-control directors]] to control the {{convert|12.7|cm|in|adj=on|sp=us}} guns, one for each side of the ship;<ref name=pt3>Parshall & Tully, p. 143</ref> the starboard-side director was on top of the island and the other director was positioned below flight deck level on the port side.<ref name=Brown20>Brown 1977, p. 20</ref>

The ship's light AA armament consisted of seven triple and five twin-gun mounts for [[license-built]] [[25 mm Hotchkiss anti-aircraft gun|Hotchkiss]] [[Type 96 25 mm AT/AA Gun|25&nbsp;mm Type 96]] AA guns. Two of the triple mounts were sited on a platform just below the forward end of the flight deck.<ref>Brown 1977, p. 21</ref> The gun was the standard Japanese light AA gun during World War II, but it suffered from severe design shortcomings that rendered it largely ineffective. According to historian Mark Stille, the weapon had many faults including an inability to "handle high-speed targets because it could not be trained or elevated fast enough by either hand or power, its sights were inadequate for high-speed targets, it possessed excessive vibration and muzzle blast, and its magazines were too small to maintain high rates of fire".<ref>Stille 2007, p. 51</ref> These {{convert|25|mm|in|adj=on|sp=us|0}} guns had an effective range of {{convert|1500|-|3000|m|yd|sp=us}}, and an effective ceiling of {{convert|5500|m|ft|sp=us}} at an elevation of +85 degrees. The maximum effective rate of fire was only between 110 and 120 rounds per minute because of the frequent need to change the fifteen-round [[magazine (firearms)|magazines]].<ref>Campbell, p. 200</ref> The Type 96 guns were controlled by five Type 95 directors, two on each side and one in the bow.<ref name=pt3/>

===Armor===
''Hiryū'' had a [[Belt armor|waterline belt]] with a maximum thickness of {{convert|150|mm|sp=us|1}} over the [[magazine (artillery)|magazine]]s that reduced to {{convert|90|mm|sp=us|1}} over the machinery spaces and the [[avgas]] storage tanks. It was backed by an internal anti-splinter [[bulkhead (partition)|bulkhead]]. The ship's [[deck (ship)|deck]] was {{convert|25|mm|sp=us}} thick over the machinery spaces and {{convert|55|mm|sp=us}} thick over the magazines and avgas storage tanks.<ref name=Brown20/>