L118 light gun


The L118 light gun is a 105 mm towed howitzer. It was originally designed and produced in the United Kingdom for the British Army in the 1970s. It has since been widely exported. The L119 and the United States Army's M119 are variants that use a different type of ammunition.
The L118 uses separate-loading cased-charge ammunition – the projectile is loaded into the gun and rammed by hand, then the cartridge with propellant is loaded behind it. The L119 and M119 use "semi-fixed" ammunition – when it is prepared for firing, the projectile is fitted into the top of the cartridge case and the shell loaded into the gun as a complete round.

History

Development

From 1961 to 1975, the British Army used the 105 mm pack howitzer L5 with L10 ordnance as its light artillery weapon, replacing the 75 mm howitzer, 4.2 inch mortar, and 25-pounder gun in eight regular artillery regiments. It fires the US M1 type ammunition. The Mod 56 was originally designed in Italy for its mountain artillery units. It was light enough to be lifted by Westland Wessex helicopters or towed by Land Rovers. It could also be dismantled, with no piece heavier than to be transported by mules or horses. It lacked range, was not notably robust, and had poor sights. Nor were its rate of fire and time to prepare for opening fire satisfactory.
In 1965, a general staff requirement was approved for a new 105 mm weapon system because the L5 pack howitzer "lacked range and lethality". Key characteristics included 6400 mil traverse by one soldier, maximum weight of, small enough size to be carried inside new Chinook helicopters and Andover transport aircraft, and ability to fire immediately after being under water for 30 minutes. The ammunition to be used was the 105 mm Fd Mk 2 ammunition used in the L13 ordnance of the gun equipment 105 mm L109. This ammunition uses electrical instead of percussion primers and is an entirely different design from the US M1 type ammunition as used in the L5 pack howitzer. The two types are not interchangeable. An early requirement was for the new weapon to use 105 mm Fd Mk 1 ammunition, which uses the M1 shell, in training. However, in 1968, this was changed to allow a different version of the weapon, which subsequently became the L119, to fire US 1935 pattern ammunition.
The new gun, soon designated "light gun", was designed by the government Royal Armament Research and Development Establishment, Fort Halstead, Kent. Prototypes were tested in 1968. It soon emerged that some increase in weight was needed for the requisite robustness, and several assemblies were substantially redesigned.
Original production, which was authorised in late 1975, was by Royal Ordnance Factory, ROF Nottingham, which has since been incorporated into BAE Systems Land and Armaments. Deliveries started in 1976.

In British service

The light gun entered service with the British Army in 1976. It was heavier than its predecessor, but helicopters that could carry it, such as the Puma and Westland Sea King, were entering service at the same time. A new vehicle, the Land Rover 101 Forward Control, was designed as its prime mover in the field. Since the end of the 1990s, the British Army has used Pinzgauer ATVs as their gun tractors. In Arctic service, and elsewhere, the gun is towed by the Hägglunds Bv 206 and is fitted with skis when over snow.
In 1982, five batteries were deployed to the Falkland Islands during the Falklands War. In the final phases of the battles around Port Stanley, these guns were firing up to 400 rounds per gun a day, mostly at "charge super", the most powerful propellant charge for which they were designed.
File:One OClock Gun.JPG|thumb|left|The One O'Clock Gun firing at Edinburgh Castle
At present, the British Army has four light gun regiments: 3rd Regiment Royal Horse Artillery, 4th Regiment Royal Artillery, 7th Regiment Royal Horse Artillery, and 29 Commando Regiment Royal Artillery. Other regiments were temporarily equipped with it for service in Afghanistan. The 14 Regiment Royal Artillery uses it for training at the Royal School of Artillery.
Four regiments of the Army Reserve, The Honourable Artillery Company, 103rd are also equipped with the light gun. Those University Officer Training Corps with "gun troops" train with the L118.
On 30 November 2001, an L118 light gun replaced a 25-pounder gun as the One O'Clock Gun in Edinburgh Castle. By tradition, this fires at one o'clock every afternoon, except on Sundays, Good Friday and Christmas Day. The light gun is also fired by 14 Regiment Royal Artillery on Remembrance Sunday and Armistice Day each year.
As of July 2017, there were 126 L118 light guns in service with the British Army.

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 25-pounder gun, 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 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. 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, it never, unlike the Abbot, had gun rules. 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. The normal cartridge has six propellant increments. 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. The 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 to reduce the minimum range at high-angle fire when this was required.
The 105 mm Fd Mk 2 rounds were the same as used with Abbot when the L118 was first introduced. The ammunition types originally or subsequently in UK service include:
  • L31 HE series is a series of 105 mm rounds which are claimed to have a 25% greater lethal area than the US 105 mm M1 HE shells.
  • *L31A1 HE round is made from forged or cold‐extruded high‐tensile steel with a single copper band and a nominal fuzed weight of. The L31A1 has two main fillings both weighing, Type A is 60:40 RDX/TNT, Type B is 55:45 RDX/TNT. Fuzes used are the L32 and L85A2 point detonating, the L33 mechanical time or the L27 variable time.
  • *L31A2 HE has a nominal fuzed weight of and its main filling is of creamed TNT. Fuzing is as with the L31A1.
  • *L31A3 HE has a nominal fuzed weight of and its main filling is of Bridgewater produced Type A 60:40 RDX/TNT and topped with TNT. Fuzing is as with the L31A1 with the addition of the L116 multi‐option fuze.
  • *L31A4 HE is available in two versions, conventional explosive and insensitive munition -compliant. The conventional explosive shell's main filling is a Eurenco RDX/TNT. The IM-compliant shell was originally designated the L50A2, its explosive filling is of ROWANEX 1100. Fuzing is either the L106A4 point detonating or the L116A1 multi-purpose fuze.
  • 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 or electronic time fuze. On falling to the ground, they generate dense white smoke for 60 seconds.
  • Target marker. These generate dense orange or red cloud 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 at about 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.
  • L50A2 HE‐IM ER features a base bleed unit, extending the range of the projectile to. The round's explosive fill is of ROWANEX 1100. Fusing is as with the L31A4.
  • L53 HE‐IM is intended to gradually replace the L31A4 round, retaining the external ballistics of the L31 series but with a shell body optimised for fragmentation. The round has a ROWANEX explosive fill. Fusing is as with the L31A4.
  • 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 has been developed.