ARMED FORCES, Royal Ordnance 105mm Light Gun Upgrade
JANE'S DEFENCE WEEKLY
DATE: 13-Oct-1999
EDITION: 1999
VOLUME/ISSUE: 032/015
BY LINE:
Christopher F Foss JDW Land Forces Editor - London
TEXT:
Royal Ordnance, in partnership with the UK Defence Evaluation and Research Agency (DERA), has developed a Mid Life Upgrade (MLU) package for the combat-proven 105mm Light Gun, which will provide lower operating and support costs.
The first pre-production example begins firing trials early next year and all new guns built from 2000/2001 will be to this standard.
The US Army's Armament Research and Development Command (ARDEC) has also contributed to the MLU based on its involvement with the US Army 119 (or M119 in US Army service) Light Artillery System Improvement Programme (LASIP). The US Army is the largest user of the 105mm Light Gun having taken delivery of 355 weapons.
Including licence production in Australia and the USA, more than 1,000 Light Guns have been built and sold to 18 countries. There are currently two versions of the Light Gun in service - the 118 and 119. The only difference between them is their barrels. A number of countries use the 119 barrel for peacetime training because of its shorter range and lower ammunition costs and switch to the 118 configuration for combat.
The 118 was developed to meet the UK Royal Artillery's requirements. It fires Royal Ordnance developed ammunition including High Explosive (HE) (L31), Illuminating (L43) and smoke (L37, L38 and L45, depending on colour). The maximum firing range for the HE projectile is 17.2km. The 119 fires standard US M1 HE semi-fixed ammunition and has a maximum range of 11.5km.
One key factor driving the 105mm MLU was that all improvements would be incorporated into new production guns and be capable of being back fitted to existing guns at unit/workshop level.
Most users tow the Light Gun with the 105mm ordnance traversed through 180º and locked into position over the rear. To become operational, the weapon must be jacked up on one side, one wheel removed and the upper part of the weapon with ordnance traversed through 180 degrees to face the front, and the wheel replaced.
The MLU gun must still be jacked up, but the wheel no longer needs to be removed. The installation of a new jointed stub axle means the complete wheel only has to be tilted to allow the upper part of the weapon and barrel to be traversed to the front. Once this has been accomplished, the wheel reverts to its normal position and the jack is removed. This new feature not only reduces the time needed to become operational but also increases user safety and reduces the crew's workload.
A new buffer and recuperator unit has been designed and installed which incorporates modern sealing technology to significantly reduce maintenance requirements. Reducing the number of component parts increases operational reliability.The unit also improves the weapon's cold weather performance.
The brakes on the existing 105mm Light Gun have been replaced by new ones designed by AP Lockheed. They are not only lighter and require little maintenance, but are free of asbestos. The gun has also been fitted with a new ruggedised master cylinder as well as new ergonomically-improved hand brake levers.
The same gearbox developed by ARDEC for the US version of the 105mm Light Gun has been fitted on the new gun.
The A-frame mounted on the forward part of the carriage has been replaced by a single strut and centre traverse lock, which holds the upper part of the weapon in place during travelling.
With fewer parts, this is more reliable, safer and easier to operate. The overall height of the system is reduced when towed with ordnance facing the front.
The steel traversing platform is mounted under the carriage weapon and weighs 96.6kg. When deployed in the firing position, the wheels of the weapon run around the outer rim, allowing the weapon to be rapidly traversed onto a new target. There is an on-going feasibility study for reducing the weight by using different materials.
An extended towing eye greatly increases the clearance between the gun and the towing vehicle. This is important to applications where the tow hook is situated under the rear of the vehicle. This design also improves gun articulation while being towed, particularly over rough terrain.
Royal Ordnance, in co-operation with Netherland's Eurometall, has developed a new round called the 105mm howitzer Extended-Range (ER) HE ERM1. This has a greater range, muzzle velocity and is more lethal than the old HE M1.
It has a maximum range of 19,000m, 64% greater than the original M1 projectile. About 45% of this can be attributed to the charge system and 19% to the base bleed unit. When used with the Royal Ordnance developed RO663A1 increment 2 charge system, the ER HE ERM1 has a maximum muzzle velocity of 707 m/s compared with the HE M1 with M67 increment 7, which has a maximum muzzle velocity of 490 m/s.
The ER HE ERM1 is 45% more lethal than the original HE ERM1. The projectile accepts any fuzes which comply with Mil Std 333-B; for example, the UK L106 or the US M739. The new rounds have a shelf-life of 10 years and can be used within a temperature range of -46º to 63º celsius.
The ER HE ERM1 has undergone extensive trials in various countries and production will begin when orders are placed.
The ammunition can be used with both the 119 Light Gun and the Dutch RDM Technology M101 upgrade, which is already used in Canada and Chile.
The Light Gun can also be fitted with the Marconi Electronic Systems Laser Inertial Alignment Pointing System (LIAPS). LIAPS reduces the time needed to come into action as no survey is required. The weapons can be distributed further apart, making them more difficult to locate and destroy. With greater accuracy, less ammunition is required.
The Royal Artillery earlier this year selected LIAPS and signed a contract for 137 systems to be delivered by 2002.
Close-up of the new axle ...
Close-up of the new axle design of the Royal Ordnance 105mm Light Gun with Mid Life Upgrade which means that the wheel no longer has to be removed to come into action.
The new ER HE ERM1 105mm ...
The new ER HE ERM1 105mm round developed by Royal Ordnance and Eurometall has greater lethality and more range.
