Type 99 cannon

Type 99 cannon. The Type 99 is a Japanese-built, gas-operated 20 mm autocannon developed for close-in weapon systems. It was designed by Japan Steel Works and entered service with the Japan Maritime Self-Defense Force in 1999. The weapon is a core component of the Phalanx CIWS Block 1B systems deployed on various JMSDF vessels for defense against anti-ship missiles and other aerial threats.

Development and history

The development of the Type 99 was initiated to provide a domestically produced alternative to the M61 Vulcan cannon used in earlier Phalanx CIWS units acquired from the United States. The project was led by Japan Steel Works under contract from the Japanese Ministry of Defense and the Technical Research and Development Institute. The design phase leveraged existing technology from the Oerlikon 20 mm cannon and incorporated lessons from the operational use of the Goalkeeper CIWS by other navies. Successful testing was completed in the late 1990s, leading to its formal adoption by the JMSDF in 1999, coinciding with the upgrade program for the Phalanx CIWS to the Block 1B standard. This development was part of a broader post-Cold War trend where nations like Japan sought greater self-sufficiency in critical defense systems.

Design and specifications

The Type 99 is a six-barreled, gas-operated rotary cannon chambered for the 20×102mm cartridge, similar to the round used by the M61 Vulcan. Its gas-operated, rotating bolt action differs from the externally powered Gatling-style mechanism of the M61 Vulcan, potentially offering reliability advantages. The weapon features a selectable rate of fire, adjustable between 200 and 450 rounds per minute, allowing for optimized ammunition conservation and target engagement. It is fed by dual 200-round linked belts, providing a ready supply for sustained engagements. The cannon is integrated with an advanced electro-optical fire control system, which includes FLIR and video tracking capabilities, and is paired with the Ku-band radar of the Phalanx CIWS. This entire system is mounted on a stabilized, trainable platform that allows for rapid engagement of high-speed targets.

Operational use

The Type 99 cannon is deployed exclusively as the main armament of the Phalanx CIWS Block 1B on major JMSDF warships. Its primary operational role is point defense against incoming anti-ship missiles such as the Exocet or the Harpoon (missile), as well as against aircraft, small surface vessels, and floating mines. These systems are installed on vessels including the Kongō-class destroyer, the Atago-class destroyer, and the Hyūga-class helicopter destroyer. The system saw a significant operational test and validation during exercises like Annualex and in joint drills with the United States Navy in the Pacific Ocean. The capability to engage surface targets, a key feature of the Block 1B upgrade, has made it a versatile asset for the JMSDF in various maritime security scenarios.

Variants

There is one primary variant of the weapon system. The Type 99 is specifically configured for naval use within the Phalanx CIWS Block 1B mount. There are no known standalone land-based or aircraft-mounted variants of the cannon. The system itself, however, is part of the broader evolution of the Phalanx CIWS, which includes earlier models using the M61 Vulcan and the subsequent land-based C-RAM system deployed by the United States Army. All operational units in Japan use the same naval specification.

Users

The sole operator of the Type 99 cannon is Japan. It is used exclusively by the Japan Maritime Self-Defense Force. The weapon system is not known to have been exported to any other country or service, including the Japan Air Self-Defense Force or the Japan Ground Self-Defense Force. Its use remains integral to the air defense network of the JMSDF surface fleet.

Category:Autocannon Category:Naval weapons of Japan Category:Cannons of Japan