M230 chain gun


The M230 Chain Gun is a 30 mm, single-barrel chain-driven autocannon, using external electrical power to cycle the weapon between shots. It was designed and manufactured originally by Hughes Helicopters in Culver City, California. The company was acquired by McDonnell Douglas Helicopters in 1985, which merged into Boeing Corporation in 1997. In 2002, it was sold again to Alliant Techsystems, which merged with Orbital Sciences Corporation in 2015 to form Orbital ATK and was, in turn, bought out by Northrop Grumman in 2018., it is produced by Northrop Grumman Innovation Systems.

Development

In 1972, Hughes Helicopters began a company-funded research effort to design a single machine gun to fire the U.S. Army's M50 round. By April 1973, the program had fired test rounds in more powerful WECOM linked ammunition, from a prototype. In January 1975 a model "C" was added, a linkless version for the proposed Advanced Attack Helicopter YAH-64; the helicopter was eventually adopted as the AH-64 Apache, with the model C as standard armament. The linked ammunition version was intended for use on the AH-1S Cobra as the M230E1, but was later dropped.

Design

Apache and DAP mounts

The M230 Chain Gun is the "Area Weapon System" on the Boeing AH-64 Apache attack helicopter and is also used on the MH-60L Direct Action Penetrator. The M230 is mounted on the chin turret. It uses a electric motor to fire linkless ammunition at a rate of 625 rounds per minute. The practical rate of fire is about 300 rounds per minute with a 10-minute cooling period as the gun is air cooled. The gun has a positive cook-off safety for open bolt clearing, and double ram prevention. Spent casings are ejected overboard through the bottom of the gun.
The mount on the AH-64 uses secondary hydraulics to move the gun. Elevation is provided via a single hydraulic actuator located on the gun's centerline just forward of the pivot point. The gun is spring-loaded to return to its centerline stowed position with the barrel angled up about eleven degrees in the event of a loss of hydraulic power. This allows the gun, which is mounted below the copilot station, to collapse cleanly into its designed space between the pilot stations in the event of a hard landing. This prevents the gun from entering the pilots stations and becoming a hazard.
The Apache is capable of carrying up to 1,200 rounds for the gun in a device known as the 12-PAK, designed and manufactured by Meggitt Defense Systems, Inc. However, utilization by the US Army of a special internal fuel tank, the Robertson IAFS, reduces this capacity to 300 rounds. The ammunition is loaded into the AH-64D Longbow Apache by armament personnel using an aircraft-mounted motorized loader and special ammunition handling tray. The AH-64A requires specialized ground support equipment for loading.
The M230 is capable of firing the 30x113 rounds used in the ADEN cannon and DEFA cannon, however, the Lightweight rounds used in the M230 are constructed with a light alloy as opposed to brass or steel cases to save weight and are in use with the US Army. The M230 rounds are not backwards compatible with weapons designed for the ADEN or DEFA rounds. The M788 rounds can be distinguished by the blue band near the nose, the M789 by a yellow stripe atop a black band and the M799 a red stripe atop a yellow band. The M799 HEI round is not used by the US Army due to the danger of a round exploding in the gun barrel. The M789 High Explosive Dual Purpose ammunition cartridge is the primary tactical round of the Apache AH-64 helicopter, widely used in current combat operations. The Apache's ability to provide accurate air support with minimal collateral damage led to increased use and volume demands for M789 ammunition.
The M789 is typically used in the M230. Each round contains of explosive charge sealed in a shaped-charge liner. The liner collapses into an armor-piercing jet of metal that is capable of penetrating of RHA at 500m. Additionally, the shell is also designed to fragment upon impact. The lethal radius against unprotected, standing targets is about under optimum conditions.

Variants

M230LF and MAWS

The M230LF, offered by Orbital ATK, is a more capable version of the Apache autocannon. Features include an anti-hangfire system, a delinking feeder that exploits linked ammunition, and an extended-length barrel, which results in greater muzzle velocity and hitting power from the same M789 HEDP and NATO standard ADEN/DEFA projectiles. The rate of fire is reduced to 200 rounds/minute and overall length decreased to. The chain gun can be installed in an enclosed turret on patrol boats and ground vehicles.
The MAWS lightweight gun system, developed in partnership with the U.S. Navy, utilizes a remotely operated M230LF in an open mount. It is controlled by a Remote Operator's Console —with either dual grips or a joystick—from a touch panel display and extended day color TV.
In February 2015, Oshkosh Defense and ATK conducted a firing demonstration of the M230LF on an Oshkosh M-ATV MRAP to demonstrate the viability and effectiveness of a medium caliber weapon system for light tactical vehicles. The live fire demonstration showcased improved accuracy in mobile engagements and improved lethality on the M-ATV using the gun, mounted on the R400S-Mk2, a 3-axis stabilized remote weapon station weighing less than. The addition of the M230LF stabilized on the RWS provides mobile precise lethality, usually reserved for heavier combat vehicles, with exceptional off-road mobility and MRAP levels of protection. Oshkosh has also fitted the M230LF to the L-ATV to fulfill the U.S. Army's light reconnaissance vehicle role.

Aircraft use