Howitzer L118

Howitzer L118

The L118 light gun is a 105 mm towed howitzer. It was originally produced for the British Army in the 1970s and has been widely exported since, including to the United States, where a modified version is known as the M119 howitzer. The proper name for it is “Gun, 105mm, Field, L118” but it is almost always just called “the light gun”.

Design

The L118 uses the L19 ordnance on the L17 carriage. The L19 ordnance is slightly shorter than the L13 used by the Abbot and hence has a slightly shorter maximum range. Also, unlike the Abbot, the barrel is autofrettaged and hence lighter.

The light gun appears to owe a number of its features to the QF 25 pounder, unsurprisingly since RARDE was the successor to the design department, Woolwich Arsenal. Among these features are its vertically sliding block breech, and a box trail instead of a split trail; a traversing platform is normally used with it. Its comparatively light weight is also attributed to the nature of the steel used in the carriage and ordnance, and other weight-reducing features, including its narrow wheelbase.

The narrow wheelbase prevents the ordnance rotating the 3200 mil (180°) required to ‘unfold’ the gun. Because of this, the gun features a knock-off hub on one side allowing the ordnance to be rotated by removing one wheel. With a well trained gun crew, this contributes approximately 30 seconds to the time required to deploy the gun. In British service, rotating the barrel for towing is optional.

When being towed in the unfolded position, the A-frame is fitted to the front transom in order to support the elevating mass. A recent modification makes it possible to keep the gun in this position indefinitely at speeds up to 40 mph (64 km/h). For long distance transport or traversing rough terrain, the barrel is reversed and clamped to the end of the trail. For storage, the gun is in the unfolded position with the barrel elevated to an angle that balances the elevated mass on the yoke and therefore relieves pressure on the elevating gears.

When first introduced in the British Royal Artillery, the L7 or L7A1 dial sight and its carrier, incorporating an integral elevation scale and internal lighting powered by Trilux nuclear light sources, was used to aim the gun for indirect fire. The L7 sight is a modified version of a German Leitz instrument. Since the light gun entered service after the introduction of field artillery computer equipment (FACE), it never, unlike the Abbot, had gun rules (large slide rule like instruments used at each gun to convert range in metres to tangent elevation in mils, taking account of muzzle velocity). Therefore, it has a single quadrant elevation scale. These optical indirect fire sights are now only used in recruit training.

The guns also have a direct fire telescope and were originally issued with a night telescope using image intensification.

Ammunition

The 105 mm Fd Mk 2 ammunition has two propelling cartridges and a blank cartridge (for saluting purposes). The normal cartridge has six propellant increments (charges 1, 2, 3, 4, 4½, and 5). Charge 4½, which is charge 5 with the blue charge three bag removed, is peculiar to the light gun and is used only for high angle fire. A separate “charge super” cartridge is used for firing to maximum range.

Both charge five and charge super project beyond the end of the metal cartridge case. Unlike the M1 ammunition, which is ‘semi fixed’ and loaded as a complete round, 105 mm Fd is ‘separate, cased’; the shell is loaded and rammed by hand, then the cartridge with propellant is loaded. By the time the L118 entered service, propellant sub-zones A and B originally used with the Abbot had been replaced by an aerodynamic spoiler (a ring slipped over the nose of shell to lodge on the ogive) to reduce the minimum range at high angle fire when this was required.

The 105 mm Fd Mk 2 projectiles were the same as used with Abbot when the L118 was first introduced. The ammunition types originally or subsequently in UK service include:

  • L31 high explosive (HE) filled with 2.5 kilograms (5.5 lb) of RDX/TNT. Conventional impact L32, L85 and L106, L27 CVT and L33 mechanical time fuzes were originally used and some are still available. The L116 multi-role (electronic) fuze is available for operations but is due to be replaced by a new multi-function fuze L166.
  • L45 smoke base ejection. This contains three canisters filled with hexachloroethane, which are ejected from the base of the shell in flight by a mechanical (L92) or electronic time fuze (L132 being replaced by L163). On falling to the ground, they generate dense white smoke for 60 seconds.
  • Target marker. These generate dense orange (L38) or red (L37) cloud (produced by a mixture of PETN HE and coloured dye) bursting in the air or on impact, and are used to designate targets e.g. for air strikes.
  • L43 illuminating. Provides a parachute flare base ejected by time fuze (L81) at about 400 metres above the ground and burns for 30 seconds.
  • L42 high explosive squash head. Used for direct fire against armoured targets or buildings, has a base fuze with tracer.
  • L41 PRAC. Inert practice shell used in training instead of HESH.
  • L50 HE. This new HE shell is slightly longer than the older shells, uses 2.9 kilograms (6.4 lb) of ROWANEX (stands for Royal Ordnance Waltham Abbey New Explosive a RDX-based formulation) insensitive plastic bonded explosive and provides significantly greater lethality, which the supplier claims is equivalent to the 155 mm HE M107
  • L52 contains four canisters filled with red phosphorus smoke.
  • L54 ‘black light’ illumination, using the same configuration as L43, to assist observation through night viewing devices.
  • L83 drill. An inert shell for non-firing training purposes.

A white phosphorus smoke shell has never been adopted by the UK for L118. A base bleed insensitive HE shell, with a maximum range of 20.6 kilometres (12.8 mi) has been developed.

Subsequent enhancements

During the early 1990s all UK L118 were fitted with a muzzle velocity measuring device (MVMD), a radar, and its power supply.

In 2002 the British Army’s L118 guns completed replacement of their optical sights with the LINAPS artillery pointing system (APS) mounted above the barrel. This is a self-contained system that uses three ring laser gyros to determine azimuth, elevation angle and trunnion tilt angle. It also includes facilities for navigation and self-survey using a global positioning system, inertial direction measurement and distance measurement. All this can be used anywhere in the world to lay the gun without external references. The outputs and inputs for APS are through the touchscreen layer’s display and control unit (LCDU) that replaced the conventional dial sight and its mount. The LCDU enables the layer to lay the gun by moving the barrel until the LCDU displays no difference between the ordered firing data and where the barrel is pointing as determined by the LINAPS sensors.

A capability enhancement program that started delivering improvements to UK guns in 2007 aimed at reducing weight and improving some components. Weight reduction measures include the replacement of some steel components by titanium, however, only some elements entered UK service. The MVMD is also more tightly coupled with the LCDU, reducing electrical power requirements.

Around 2010, new direct fire sights for longer range use were introduced for service in Afghanistan. These comprise a sniper’s telescopic sight and a new night sight.

At the end of 2011, a new LCDU with a slightly larger touchscreen was ordered. It may enable data transfer from FC-BISA and include the NATO armament ballistic kernel (NABK) for direct fire shooting.

Variants

L119

The L119 variant has a different barrel (a slightly shorter L20 ordnance with a percussion firing mechanism) for firing the ubiquitous US M1 type ammunition (UK 105 mm How), giving the gun a max range of 11,400 metres (12,500 yd). In British service, the L119 was used only for training at the Royal School of Artillery while stocks of 105 mm How lasted, and the last British L119s were retired in 2005. However, the L119 is popular with many export customers who still rely on M1 ammunition.

M119

The L119 was further modified and produced under licence for the United States Army. The most recent version is the M119A3 introduced in 2013 with a digital fire-control system and GPS-aided inertial navigation unit using software derived from the M777A2.

Other variants

During the 1970s a third variant, with the L21 ordnance, was developed and prototypes produced. This was for Switzerland and used Swiss pattern 105 mm ammunition. It did not enter service.

The Indian 105 mm light field gun appears to share many features with the UK equipment. In the late 1960s India introduced the Value Engineered Abbot variant with the 105 mm Fd ammunition; this led to the 105 mm field gun (India), which appears to have some light gun features in its elevating mass, although its platform is 25-pr like. The 105 mm light field gun is much more like L118, although somewhat heavier.

In 1989, the L119 entered service with the Australian Army named the “Hamel Gun” to replace the M2A2. The gun was manufactured under licence in Australia for the Australian and New Zealand armies using mostly Australian produced components. Plans to produce 105 mm field ammunition were shelved.

105 mm saluting gun: The British Army has a number of dedicated saluting guns for ceremonial purposes. Based on the standard L118, these saluting guns are modified to exclusively fire blank cartridges, are not fitted with the APS system and are easily distinguished from the field gun variant by their distinctive bronze green paintwork, chromed muzzle brake and breech.

Specifications

Weight 1,858 kg (4,096 lb)
Length 8.8 m (28 ft 10 in)
Barrel length 37 calibers[1]
Width 1.78 m (5 ft 10 in)
Height 2.13 m (7 ft)
Crew 6 (normal), 4 (reduced)

Calibre 105 mm (4.1 in)
Breech vertical sliding block with electric firing mechanism
Recoil hydropneumatic
Carriage box trail, firing with wheels on the ground or platform
Elevation -5.625° (-100 mils) to 70.3125° (1,250 mils)
Traverse 360° (6,400 mils) on its platform and top traverse 5.625° (100 mils) left or right
Rate of fire 6-8 rounds per minute
Muzzle velocity maximum 708 m/s (2,320 ft/s)
Maximum range 17,200 m (18,800 yd) (20.6 km (22,500 yd) extended range using base bleed)
Sights optical dial sight on reciprocating mount or inertial using 3 ring laser gyros

Operators

Related Armament

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