AS-90

Infobox Weapon
name=AS-90


caption=155 mm self-propelled guns in Basra
origin=flagcountry|United Kingdom
type=Self-propelled artillery
is_vehicle=yes
is_UK=yes
length=9.07 m (29.75 ft)
width=3.5 m (11.48 ft)
height=2.49 m (8.16 ft)
weight=45 tons (100,800 lbs)
suspension=hydropneumatic (Hydrogas)
speed=53 km/h (33 mph)
vehicle_range=420km (261 mi)
on road
primary_armament =155 mm L31 39 calibre gun48 rounds
secondary_armament=7.62 mm NATO L7 GPMG
armour=max. 17 mm (.66 in) steel
engine=Cummins VTA903T V8 diesel
crew=5 (Commander, driver, three gun crew)
engine_power= 660 hp (492.16 kW)
pw_ratio= 14.66 hp/tonne

The AS-90 (Artillery System for the 1990s) is a lightly-armoured self-propelled artillery piece used by the British Army. It was first delivered in 1993.

The AS90 is used by five regiments of the Royal Horse Artillery and Royal Artillery: 1 RHA, 3 RHA, 4 Regt RA, 19 Regt RA and 26 Regt RA, replacing the 105 mm FV433 Abbot SPG, the M109 155 mm SPG or the FH-70 155 mm towed gun.

AS 90 was designed and built by the Armaments division of Vickers Shipbuilding and Engineering (VSEL, owned by BAE Systems since 1999), who provided 179 vehicles from 1992-95 at a cost of £300 million.

In 2002 BAE systems were contracted to upgrade 96 British Army AS90s to a 52 calibre gun to push the unassisted range to 30 km and with long-range ERA ammunition to 60 to 80km. [ [http://www.armedforces.co.uk/army/listings/l0046.html Armed Forces - a6a4 - British Army - Artillery - AS 90] ] However, due to the inability of the selected bi-modular charge system from Somchem of South Africa to meet the requirement for insensitive munitions this project was terminated. [ [http://www.army-technology.com/projects/as90/ Army Technology - AS90 BRaveheart 155mm - Self Propelled Howitzer] ]

Development

AS90 started in the mid 1980s as a private venture on the 'gamble' that the tri-national SP70 would fail. When this duly occurred, the Ministry of Defence (MoD) issued a cardinal point specification on one page for a new 155 mm SPG. Four tenders were submitted, and AS90 was the only offer that was not 'brochureware'. The MoD was also required to consider the US "Paladin", an upgraded M109 howitzer.

The MoD is investigating a proposal from BAE Systems to "up gun" the Royal Navy's main shipboard gun armament, the 4.5 inch (114 mm) Mark 8 naval gun, to accept the 155mm gun barrel and breech from the AS-90. [ [http://www.baesystems.com/Newsroom/NewsReleases/autoGen_1071114103911.html 155MM Study Looks To Pack More Punch Into The Royal Navy's Fleet] BAe Systems Press release, 14 December 2007 ] This would introduce a common gun caliber for the British Army and Royal Navy, helping with ammunition logistics, and encouraging joint Army-Navy development of extended range and precision guided shells. [ [http://www.mod.uk/DefenceInternet/DefenceNews/EquipmentAndLogistics/ArmyToGetNewPrecisionsearchAndDestroyAntiarmourWeapon.htm Army to get new precision "search and destroy" anti-armour weapon] MoD Press release, 20 November 2007 ]

Design

In 1963 certain NATO nations, including UK, agreed a Ballistics Memorandum of Understanding for a 155mm 39 calibre ordnance and a baseline projectile with the shape used for the US M549 rocket assisted shell. The AS90 uses a conforming 39 calibre barrel which fires the L15 unassisted projectile out to a range of 24.7 km. However, this was a new design of ordnance and uses a split sliding block breech with Crossley obturation, instead of the more usual screw breech, to permit bagged charges (no metal cartridge cases). The breech mechanism has a primer magazine holding 18 primers.

The vehicle is fitted with an autonomous navigation and gun laying system (AGLS) and all main turret functions are controlled by a Turret Control Computer (TCC). Every gun is fitted with a radar Muzzle Velocity Measuring Device.

It is fitted with an auxiliary power unit to eliminate the need to run the main engine to keep the batteries charged while stationary; electrical servos drive the automated elevation, traverse, magazine and loader as well as power for electronics and communications.

Characteristics

* Crew: 5, driver plus 4 gun crew
* Length: 9.07 m
* Width: 3.3 m
* Height: 3.0 m
* Armour: 17 mm (maximum, steel)
* Weight: 45 tons
* Calibre: 155 mm
* Range: 24.7 km (39 cal), 30 km (52 cal) standard charges
* Rate of fire: 3 rounds in 10 seconds (burst), 6 rounds per minute for 3 minutes (intense), 2 rounds per minute for 60 minutes (sustained)
* Secondary armament: 7.62 mm L7 GPMG
* Ammunition carried: 48 projectiles and charges (31 turret and 17 hull), 1000 MG rounds
* Main Engine: Cummins VTA903T 660bhp 90 degree, v8, 4 stroke, liquid cooled, turbo diesel,
* Max Speed: 55 km/h (Road)
* Range: 370 km or 231 miles (Road)
* Ground clearance: 0.41 m; Gradient: 60°; Vertical obstacle: 0.75 m; Trench crossing: 110 inches; Fording depth: 1.5 m

Variants

AS-90D - Modified for desert use. Thermal protection for crew and extra cooling for engine and machinery. Tracks adapted for reduced wear in sandy conditions

AS-90 "Braveheart" - Basically the AS-90, but fitted with the 52 calibre length gun. This project was terminated due to non-compliant propelling charges.

Haubicoarmata "Krab" - (eng."Howitzer-cannon Crab") Licensed "Braveheart" turret on a Polish heavily modified chassis of a T-72 tank, with modern "Azalia" BMS. Designed and integrated in Poland, by Huta Stalowa Wola and WB Electronics. As of early 2007, two Krab ("Crab") prototypes are built, and successfully completed all required evaluations and state acceptance trials. Order for 48 of 80 projected units for Polish Armed Forces is expected in 2008. Due to the use of a modified T-72 chasis the Indian Army is interested in this design.

References