Chiyoda-class aircraft carrier

Line drawing of Chiyoda.
Class overview
Name:	Chiyoda-class aircraft carrier
Builders:	Elissa-Arishat Cooperative Naval Group Hanno Line Shipwrights - Abidjan Manila Naval Arsenal New Dublin Navy Yard New Washington Navy Yard Sasebo Naval Arsenal
Operators:	Carthage Japan
Preceded by:	Ryūjō-class aircraft carrier Libya-class aircraft carrier
Cost:	NSD$3.6 billion (FY2014)
Built:	2002-present
In commission:	12 March 2006
Planned:	106
Building:	14
Completed:	46
Active:	46
General characteristics
Type:	Aircraft carrier
Displacement:	68,000 tonnes (full)
Length:	287.0 m (941.6 ft)
Beam:	39.5 m (130 ft) (waterline) 74.8 m (245 ft) (flight deck)
Draft:	10.2 m (33 ft)
Installed power:	2 × Ishikawajima-Harima S3 gas turbines (50 MW (67,000 hp) each) 4 × Daihatsu 16DKM-50e diesel engines (12 MW (16,000 hp) each)
Propulsion:	4 × Riken-Honda electric motors powering 5.2 m (17 ft) fixed-pitch propellers (30 MW (40,000 hp) each)
Speed:	32 knots max, 20 knots cruise
Range:	19,000 km (10,000 nmi) at 20 knots
Complement:	Ship's company: 720 Air wing: 1,300 Mission personnel: Up to 250 Max berth capacity: 2,500
Sensors and processing systems:	Type 10-AM C/S-band multifunction radar Type 11 No. 2 X-band surface search radar Type 10 X-band tracking and fire control radar Type 4 X-band navigation radar Type 12 sonar array Type 9 towed array sonar
Electronic warfare & decoys:	Type 34 electronic warfare suite 4 × Mark 40 Integrated Countermeasure Dispenser Mark 111 missile decoy SR/ENS-670 torpedo decoy Type 16 torpedo interceptor
Armament:	Missiles 4 × 8-cell Mark 21 vertical launch system 2 × 24-cell Mark 99 Rolling airframe missile launchers Guns 2 × 76 mm (3 in)/70 Mark 22 Rev. 3 1 × 35 mm CRA-952 autocannon 4 × 15.5 mm CRA-334 autocannon Torpedoes 2 × 324 mm Mark 37 integrated torpedo tubes
Aircraft carried:	Up to 60 fixed-wing and helicopters
Aviation facilities:	2 × EMALS 2 × deck-edge elevator

The Chiyoda class aircraft carriers (千代田型航空母艦 Chiyoda-gata kōkūbokan) are a class of aircraft carrier in service with the Imperial Japanese Navy and the Punic Navy. The class was originally designed to replace the Taihō-class in Japanese service until the development and adoption of the Carthaginian Leptis Magna-class. As a a result, the design was modified with a focus on anti-subamrine warfare and was developed as a replacement for the Ryūjō-class light carrier. Under the terms of the 1998 Naval Cooperation Agreement, the Punic Navy agreed to adopt the design as a replacement for the retired Libya-class fleet carrier in exchange for Japanese support for the Leptis Magna-class.

Development of the design began in 1989 as a planned replacement for the Taihō-class aircraft carriers in service with the IJN. The original concept was expected to displace 95,000-100,000 tonnes and included nuclear propulsion and CATOBAR facilities, with similar capabilities to other supercarriers. The 1995 Great Hanshin Earthquake forced the Japanese Navy to put design work on hold due to significant damage to the Kobe Reactor Test Facility and in 1998 Japan and Carthage signed the Naval Cooperation Agreement, laying out the framework for the transfer of technology and designs between the two nations. The basic design was reworked into a smaller carrier with conventional propulsion designed for anti-submarine warfare and sea control operating in support of larger attack carriers.

Chiyoda was laid down in 2001 and entered service on March 12, 2006. Since entering service, the class has participated in a number of operations, including the Oceanian Incident and the San Domingo Civil War. The design currently displaces up to 68,000 tonnes but incorporates a growth margin permitting an increase to up to 75,000 tonnes over time. Aircraft facilities include two catapults and two elevators supporting an air wing of up to 60 aircraft. Total development costs for the Chiyoda-class are expected to be ¥422 billion.

History

The Imperial Japanese Navy began formulating concepts for a new fleet carrier design to replace the nuclear Taihō-class as early as 1981, barely half a decade after the first ships of the class had entered commission in 1976. As a result of their lengthy construction period the Taihō-class entered service too late for service in the Northern War and the first ships of the class lacked the design improvements later proposed as a result of wartime experience. Like the Punic Navy the IJN realized that improving survivability was of critical importance and moderate modifications were made to later Taihō-class ships, although a new design incorporating such changes at a structural level was desired. The constrained waters of Southeast Asia in particular made survivability against missile and torpedo attacks a key design criterion.

With the Taihō-class just entering service, political support for another new design was insufficient for a new program. Instead, a number of design proposals were drafted internally for evaluation, considering features for incorporation in future designs. Sixteen draft proposals were created between 1981 and 1987 by the naval architects at the Kure and Yokosuka Naval Arsenals, ranging from 80,000-120,000 tonnes displacement. Also considered was the ideal size and displacement of a fleet carrier from a lifecycle cost perspective. Design input was also received from the Punic Navy including a draft design for the Large Survivable Attack Carrier (LSAC) proposed for but not funded by the Carthaginian government. By 1988, the IJN had formulated a more concrete notion of its plans for a future carrier design and prepared a major lobbying effort for political support.

In 1990, after a period of intense lobbying by the Navy and commercial shipbuilding interests, the National Diet approved funding for the formal design of a new fleet carrier to replace the Taihō-class designated Project G40. The new design would be the IJN's second-generation nuclear carrier design, intended to supplement and later replace the first-generation Taihō-class and incorporating all of the design improvements studied over the course of the previous decade. The design phase was expected to last until 1993 at which point long-lead items could be ordered with the first ship expected to be laid down in 1997 and completed in the mid-2000s, in time to replace the last members of the conventionally-powered Sōryū-class carriers.

Three final designs were produced under the G40 Project, displacing 95,000 (G40-1), 105,000 (G40-2), and 115,000 tonnes (G40-3) and carrying between 80 and 95 aircraft under existing Japanese practice. The G40-3 115,000 tonne design was considered the preferred option as it provided the most room for growth and had additional space for munitions and fuel, extending deployment periods. The G40-2 105,000 tonne design was considered adequate for the Navy's needs and a close second choice if construction funding would not permit the approval of the 115,000 tonne design. The G40-1 95,000 tonne design was considered too small for the Navy's needs and was not pursued further. In 1994, design G40-2 was approved for construction with keel-laying planned for 1997-1998.

Setbacks

Development work on components for the new ships had begun as early as 1990, including a new nuclear reactor design and new systems such as an electromagnetic aircraft catapult system. In 1995, the Great Hanshin Earthquake struck the Hanshin area, causing widespread damage including to the Kobe Reactor Test Facility. Damage caused by the earthquake was expected to set reactor testing and certification back several years on top of the diversion of funds to earthquake relief. The expected delays put the expected completion date of the first new G40 carrier in question with no firm timeline for completion of the reactor testing.