Crossbow CIWS

Crossbow CIWS
A Crossbow Block 2 aboard the GCNS Vengeance during a live fire test.
Type	Close-in weapon system
Place of origin	Hulie
Service history
In service	1980–present
Used by	See Operators
Production history
Designer	Xianzai Arsenal
Designed	1975–1979
Manufacturer	Xianzai Arsenal
Unit cost	CL₡6.5 million (FY2012)
Produced	1979–present
Variants	See Variants
Specifications
Weight	Block 0: 7,271 kg (16,030 lb) (inc. ammunition) Block 1/CRAMS: 8,339 kg (18,384 lb) (inc. ammunition) Block 2: 9,330 kg (20,570 lb) (inc. ammunition)
Barrel length	2.8 m (9.2 ft)
Height	3.53 m (11.6 ft) (above deck)
Crew	Automated, with human oversight
Shell	Armour-piercing discarding sabot (Block 0/1/2) High Explosive Incendiary Tracer, Self-Destruct (CRAMS)
Shell weight	0.62 kg (1.4 lb) (APDS) 0.67 kg (1.5 lb) (HEIT-SD)
Calibre	30×173mm
Barrels	7-barrels (Block 0/1, CRAMS) 11-barrels (Block 2)
Action	Hydraulically-driven
Elevation	−10°/+80° (Block 0) −25°/+85° (Block 1/2, CRAMS)
Traverse	360°
Rate of fire	1,200−4,200 rounds/minute (Block 0/1, CRAMS) 11,000 rounds/minute (Block 2)
Muzzle velocity	1,150 m/s (3,800 ft/s) (APDS) 1,021 m/s (3,350 ft/s) (HEIT-SD)
Effective firing range	1−1.5 km (0.62–0.93 mi)
Maximum firing range	5 km (3.1 mi)
Feed system	Block 0: One ammunition drum, holding 640 rounds Block 1/CRAMS: Two ammunition drums, each holding 500 rounds (total 1000 rounds) Block 2: Two ammunition drums, each holding 640 rounds (total 1280 rounds)
Main armament	1 × AGU-730 30 mm seven-barrel rotary cannon (Block 0/1, CRAMS) 1 × AGU-1130 30 mm eleven-barrel rotary cannon (Block 2)
Guidance system	J-band radar Electro-optical fire control system

The Crossbow CIWS (pronounced "sea-whiz") is a Chilokveri naval close-in weapon system (CIWS) introduced in 1980. Built around the AGU-730 or AGU-1130 30 mm rotary cannon and J-band radar mounted on a single unit, the Crossbow is a completely autonomous weapons system designed for the terminal or point defence of ships against missiles, aircraft, and small, fast-maneuvering surface vessels. Once activated, each turret is capable of automatically searching, detecting, tracking, and engaging threats, including the selection of the next target. A land variant known as the CRAMS (Counter-Rocket, Artillery, and Mortar System) has also been developed for the short range missile defense role to protect military bases against rockets, artillery and mortar fire. The Crossbow is expected to remain in service with the Grand Chilokveri Navy until at least 2025.

History

Development

The ADW-2 prototype demonstrated to the HPLANF in 1978.

Development of the Crossbow close-in weapons system began in 1975 as the Seashield, which was intended to create an automated weapon to serve as the last line of defence against missiles and aircraft for the HPLANF's warships. Xianzai Arsenal partnered with Atlas Electronics, which provided the radar and fire-control system, to deliver the prototype ADW-2 unit in late 1978. During demonstrations to the Huliean People's Liberation Army Naval Force, the model exceeded all performance requirements; however, the HPLANF requested that the system's reliability and maintenance be improved upon. A further operational evaluation was successfully conducted with the CIWS installed aboard the destroyer Fei Luhng in 1979, after which the weapon was approved for production under the new designation of Crossbow.

Operational history

The Crossbow's point defence capabilities have been consistently proven during live-fire trials since being accepted into service. During one such live-fire exercise, the Crossbow successfully eliminated four target drones simulating two pairs of sea-skimming anti-ship missiles fired five seconds apart, with each engagement lasting for only 0.2 seconds. The Crossbow has also been used against pirate boats and skiffs during anti-piracy patrols by the Grand Chilokveri Navy.

Design

The Crossbow consists of a 30 mm rotary cannon slaved to a turret-mounted radar and electro-optical sensors. The system was designed to be a largely self-contained system with only minimal shipboard inputs (i.e. electrical power and water for electronics cooling) needed for the CIWS to function. Thus, the Crossbow is designed to be capable of functioning despite potentially critical damage to the ship it is installed on.

Armament

The Crossbow CIWS' primary armament is either the AGU-730 7-barreled 30 mm rotary cannon or in the case of the Crossbow Block 2, the AGU-730's 11-barreled successor the AGU-1130. The AGU-730 fires the 30×173mm cartridge and has a variable fire rate of 1,200, 2,100 or 4,200 rounds per minute, while the AGU-1130 has a maximum fire rate of up to 11,000 rounds per minute. The 30 mm armour-piercing discarding sabot (APDS) rounds fired by the Crossbow consist of a 21 mm conical depleted uranium penetrator encased in a nylon sabot, and have a muzzle velocity of approximately 1,150 m/s. The Crossbow's APDS rounds are designed to either detonate a missile's warhead or completely obliterate a missile's airframe through sheer weight of fire in order to prevent, thus preventing damage to the ship. It is rare for the Crossbow to maintain sustained rates of fire beyond one minute at 4,200 rounds per minute or higher as the heat generated would begin melting the rifling of the barrels and cause excessive barrel wear. Ammunition is linkless and stored in external ammunition drums on the side of the turret. Depending on the variant, a Crossbow CIWS may be equipped with a single 640-round drum (Block 0), two 500-round drums, (Block 1, CRAMS) or two 640-round drums (Block 2).

Fire-control system

The Crossbow is directed by a J-band radar mounted on the top left of the turret for tracking and engagement, as well as an electro-optical fire control system in the form of a sensor filled ball in a U-shaped mount on the turret's top right. The 3D J-band PESA radar incorporates a total of 169 transceivers and can track up to 30 targets simultaneously. The radar is steered mechanically in the horizontal azimuth, while the beam is steered electronically in the vertical plane. The system is capable of tracking a typical sea-skimming target with a cross-section of 0.1 m² at a range of 8 km, which is further extended to 11.5 km for an fighter-sized target of 1 m² in radar cross section. However, targets are only able to be engaged at a range of 3 km or less due to the limited range of the gun. During an engagement, the radar tracks the splashes made by the 30 mm rounds to help "walk" the Crossbow onto the target. The electro-optical unit provides a visual fallback for the system operator in the case of manual engagement and comprises a colour camera, forward-looking IR sensor and laser rangefinder. The EO system is able to track targets up to 6 km out.

As a completely autonomous, closed-loop system, the Crossbow has a faster reaction time than CIWS which require the input of ship-mounted radars for engagement. Nevertheless, the Crossbow is compatible for integration with Chilokveri combat data systems such as AEGIS without further modifications. During normal operations however, the system relies on its own sensors and data to determine whether a contact is a threat based upon a contact's speed and heading. The system is also able to independently rule out friendly traces using identification friend or foe (IFF) functionality.

Variants

Block 0

The original variant of the Crossbow. The first generation versions lacked a forward-looking infrared (FLIR) sensor and had only marginal interception capabilities against surface targets.

Block 1

A Block 1B Crossbow onboard the GCNS Ban Kou.

The Block 1 upgrade was rolled out in 1989 to increase the Crossbow's ability to counter supersonic anti-ship missiles then entering service with foreign navies. This version saw improvements to the system's radar and computing power, the AGU-730's ammunition feed system and number of rounds loaded, and an increase in the CIWS's elevation range to from −10°/+80° to −25°/+85°. Block 1A added further improvements to the electronics in the form of a new computer system. The Block 1B upgrade introduced a forward-looking infrared (FLIR) sensor for the first time, which allowed the Crossbow to serve as an effective defence against surface as well as aerial targets. In addition to providing a defensive capability against boat swarms or suicide boat attacks, the FLIR also allows operators to visually identify and manually target threats. As of 2015, all Block 0 and Block 1 Crossbow CIWS had been upgraded to the Block 1B standard.

Block 2

Further development of the Crossbow CIWS led to the Crossbow Block 2, which was first shown in 2013. Though the Block 2 still fires 30×173mm rounds, the Block 2 uses the 11-barreled AGU-1130 30 mm rotary cannon rather than the 7-barreled AGU-730 as its primary weapon. As a result, the Block 2 has a fire rate more than twice that of the preceding blocks- 11,000 rounds per minute vs 4,200 rounds per minute. To sustain such a high rate of fire, the Block 2 also has one additional ammunition drum compared to Block 0/1 Crossbow variants for a total of 1,280 rounds (640 rounds per drum). The Block 2 has a reported efficiency of 96% against Mach 4 anti-ship missiles according to publicly available sources.

CRAMS

The CRAMS is the land-based version of the Crossbow CIWS.

The CRAMS (Counter-Rocket, Artillery, and Mortar System) is a terrestrial development of the Crossbow Block 1B for short-range defence of military bases and facilities against rocket, artillery, and mortar rounds. Each CRAMS gun unit reportedly carries enough ammunition for 48 engagements and has an effective range of up to 3.5 km (2.2 mi). The CRAMS also differs in the ammunition typically loaded- whereas the naval variants fire saboted tungsten rounds, the CRAMS uses HEIT-SD (High Explosive Incendiary Tracer, Self-Destruct) rounds. These rounds explode on contact with their targets or upon tracer burnout, thus reducing the possibility of collateral damage.

Each system consists of six truck-mounted Crossbow CIWS units with their own attached generator and power supply, a central ground control unit for target designation, and two 3D radar sensor units for surveillance and tracking. The entire CRAMS is fully automated, with no need for operator input once safeties are released. CRAMS was first adopted by the National Chilokveri Air Force in 2009 at a cost of ₡73.6 million per system, and was later adopted by the Supreme Army of Chilokver in 2011.

Operators

Current operators

• Chilokver
  • Grand Chilokveri Navy – The Crossbow CIWS is installed onboard all major surface combatants of the Grand Chilokveri Navy. All units have been updated to the Block 1B standard as of 2015, while the Block 2 variant has only been installed on the Vengeance-class aircraft carriers and the GCNS Touchi to date.
  • National Chilokveri Air Force – The CRAMS has replaced the Skyguard area defence system in the short-range air protection role for all National Chilokveri Air Force bases.
  • Supreme Army of Chilokver – The Supreme Army of Chilokver took delivery of its first CRAMS system in 2011.

Former operators

• People's Republic of Hulie
  • Huliean People's Liberation Army Naval Force – The Crossbow CIWS was installed aboard the Huliean People's Liberation Army Naval Force's Chung Luhng class, Seuih Hohk class, Gipguk class and Mukhak-class destroyers, Daaih Fuhng class and Fei Ying-class helicopter destroyers, as well as the HPLANF'S Min Ha-class frigates.

Specifications (Block 2)

• Gun: 1 × AGU-1130 30 mm eleven-barrel rotary cannon
• Height: 3.53 m
• Weight: 5,533 kg (without ammunition); 9,330 kg (total)
• Elevation: +85° to −25°
• Muzzle velocity: 1,150 m/s (APDS round)
• Rotation speed: 95°/s
• Rate of fire: Selectable, up to 170 rounds/second (10,200 rounds/minute)
• Maximum burst size: 4,200 rounds
• Ammunition: 1,280 linkless APDS rounds in 2 ammunition drums
• Weapons range: 350 to between 1,500 and 2,000 meters dependent on ammunition
• Radar: J band PESA radar
• Optical system: EO/FLIR sensors

See also

• ADW-1 anti-aircraft gun