M777A2 LW155 Lightweight 155mm towed howitzer technical data

: 06 January 2020

M777A2 LW155 lightweight 155mm towed howitzer

Description

Technical Data

Specifications

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Description

The M777A2 is an improved version of the standard M777 lightweight 155mm towed howitzer (referred as LW155 in U.S. army) designed and manufactured by the Company BAE Systems. The M777A2 is a towed 155 mm Howitzer jointly developed by the U.S. Army and U.S. Marine Corps to replace the M198 155mm towed howitzer. It is the first ground combat system whose major structures are made of high-strength titanium alloy resulting in a weight savings of 3,175 kg in comparison to the M198 155 mm Howitzer. The M777A2 incorporates innovative design technologies that reduces system weight to less than 4,500 kg while increases mobility, survivability, deployability, and sustainability for expeditionary operations. The main feature of the M777A2 is the possibility to fire the M982 Excalibur Guided Projectile thanks to a new software update. The Lightweight 155 mm Howitzer System (LW155) provides direct, reinforcing and general artillery fire support to maneuver forces. It can be easily transported by air in a number of transport aircraft including the C-130, C-141, C-5 and C-160 Transall. It can also be transported slung under the UH-60L/UH-60M Black Hawk and CH-53E/CH-53D helicopters and the MV-22 Osprey. The M777A2 is in service with the U.S. Army and Marine Corps and its also used by Australia and Canada. In December 2016, United States has announced a foreign military sale for the delivery of 145 M777A2 lightweight howitzers to the Indian Ministry of Defence.

Variants:

- M777: first version of the lightweight 155mm towed howitzer with optical fire control
- M777A1: digitisation upgrades with the addition of an on-board power source, satellite global positioning, inertial navigation, radio, Gun Display Unit (GDU) and Section Chief Assembly (SCA).
- M777ER: Experimental upgrade created by the Extended Range Cannon Artillery (ERCA) project modified with a 52-caliber barrel, adding 1.8 m to the cannon and less than 450 kg to the overall system, extending range from 30 to 70 km.

Technical Data

Gun

The M777A2 lightweight 155mmm towed howitzer uses a 155 mm/39 calibre ordnance using the same barrel as the US Army M109A6 self-propelled howitzer. It can be elevated to 71º and depressed to -3º. with traverse left and right of 23°. In July 2016, U.S. Marine has tested the M777A2 fitted with a M776 Chrome Tubes which helps to extend the life of the tube by two to three times and has prevented buildup of residue within the bore during controlled testing. The elevating mass comprises two sub-assemblies, the cradle and the cannon tube assembly. The cradle includes four extruded titanium tubes, an accumulator, two recoil cylinders and balancing gear. The cannon tube assembly includes the cannon tube, muzzle brake, towing eye, primer feed mechanism and screw breech. The M777A2 system makes extensive use of hydraulics to operate the breech, loading tray and suspension system to reduce crew size and fatigue. Additionally, the M777A2 provides significant time savings for displacement and emplacement. Its primer feed mechanism supports a maximum firing rate of four rounds per minute and a sustained rate of two rounds per minute. In firing position, two stabilisers are deployed at the front and two split trails fitted with self-digging spades and dampers at the rear. A small hydraulic hand pump is installed at each wheel station to raise and lower the system into and out of action. The M777A2 is operated by five military personnel to handle the various functions of the gun. It can be ready to fire in less than three minutes and can leave his firing position in the same time.

Ammunition

The M777A2 lightweight 155mmm towed howitzer can fire the full ranges of U.S. 155mm ammunition including unassisted projectiles to a range of 24 km and assisted projectiles to 30 km. With the upgraded fire controls system, it can also fire Excalibur Precision 155 mm Projectiles, Global Positioning System (GPS)-guided, extended-range artillery projectile M982 and M982A1 at a maximum range of 40 km. The target, platform location and GPS-specific data are entered into the projectile’s mission computer through an Enhanced Portable Inductive Artillery Fuse Setter. Excalibur uses a jam-resistant internal GPS receiver to update the inertial navigation system, providing precision in-flight guidance and dramatically improving accuracy of less than 2 meters miss distance regardless of range. Excalibur has three fuse options (point-detonation, point-detonation-delay and height-of-burst) and is employable in all weather conditions and terrain. Excalibur’s capability allows for first round effects on target while simultaneously minimizing the number of rounds required to engage targets and minimizing collateral damage.

Mobility

The M777A2 barrel is mounted on a carriage which includes two main components, the body and the saddle. Mounted on either side of the body is a hydro-gas suspension unit fitted with stub axle and one aluminum road wheel on each side. In travel position, the M777A2 is towed by its muzzle by a military truck. which has a capacity of 2 tone minimum. In the US Army and Marine corps, the M777A2 is towed by the 7-ton Medium Tactical Vehicle Replacement (MTVR) truck.

Accessories

The M777A2 lightweight 155mmm towed howitzer has a Digital Fire Control System (DFCS) that includes an inertial navigation unit with Global Positioning System backup to allow it to self-locate. The DFCS also includes a mission computer, displays and digital communications. Software upgrades incorporating the Enhanced Portable Inductive Artillery Fuse Setter and the Excalibur Platform Integration Kit hardware give the M777A2 the capability to program and fire the Excalibur precision-guided munition. The M777A2’s Digital Fire Control System (DFCS) is capable of determining onboard ballistic computations within 1 mil. The DFCS uses a global positioning system, an inertial navigation unit, and a vehicle motion sensor to accurately locate and orient the weapon thus improving precision and responsiveness. The system integrates radios for voice and digital communications as well as a chief of section display, which aids in navigation during movement when mounted in the cab of the prime mover. The system’s mission computer processes the fire mission and provides directional commands to the displays of the onboard gunner and section chief.

Specifications