An enhanced version of the Howitzer, the Desert AS90, has been built to provide high capability in arduous desert conditions. The Desert AS90 has undergone successful trials in the Arizona Desert in 1994 and in Kuwait and Saudi Arabia in 1996.

BAE Systems has signed a license manufacturing agreement with HSW (Huta Stalowa Wola) of Poland for the production of the Desert AS90, called AS90 Braveheart. The AS90 turret is to be fitted to a Polish built chassis for the Polish Army. The first two of a possible 72 systems will be built by BAE SYSTEMS.

The crew consists of the driver plus four or three operators in the cupola, a commander, a gun layer and an ammunition loader.

BAE SYSTEMS has been awarded a contract to upgrade 96 of the British Army AS90's with a 155mm/52 calibre Extended Range Ordnance/Modular Charge System (ERO/MCS). The Royal Ordnance division of BAE SYSTEMS will manufacture the new 52 calibre barrel which will give an increased range of 40 km, and Somchem division of Denel will be responsible for the Modular Charge System which will be manufactured in South Africa. The upgraded AS90's are expected to enter service in 2003.

The AS90 is fitted with a 155 mm 39 or 52 calibre gun barrel. In trials, two AS90 howitzers were able to deliver a total payload of 261 kg onto a single target in less than 10 seconds. An automated loading system enables the gun to fire with a burst rate of 3 rounds in under 10 seconds, an intense rate of 6 rounds per minute in three minutes and a sustained rate of 2 rounds per minute.

The gun, which does not require stabilising spades, is equipped with a recoil and hydrogas suspension system which allows the turret to traverse and fire through the full 360 degrees. A Dynamic Reference Unit (DRU) and electronic compensation for tilt of the vehicle are used for accurate orientation of the weapon system.

The range is 24.7 km using conventional ammunition. The AS90 also fires assisted rounds which provide an extended range to 30 km. Fitting a 52 calibre barrel instead of the standard 39 calibre extends the range beyond 40 km. An automated ammunition handling system is included in the current upgrade programme.

The layer's station is equipped with a Direct Fire Sight from Avimo for direct day and night firing. For indirect firing an Automatic Gun Laying System (AGLS) with electronic elevation and traverse drives provide laying to an accuracy of 1 mil (angle 3.375 minutes) and rapid target engagement. The Layer's Display Unit (LDU) was designed by VSEL. The commander's station is equipped with a separate sight.

A barrel cooling system to provide higher maximum firing rates and a ballistic computation system are being developed. A Global Positioning System (GPS) has been successfully trialled on the vehicle

The vehicle is of all-welded steel armour construction, which is rated to withstand impact by 7.62 mm and 14.5 mm armour piercing shells and 152 mm shell fragments. A system for increased ballistic protection against top attack by current generation anti-tank missiles is being developed.

The Desert AS90 has a thermal cover installed on the turret roof and solar reflective paint. The thermal blanket provides protection for the crew against hot metal burns.

The vehicle is powered by a 660 hp V8 diesel engine from Cummins, coupled to a ZF Gears Ltd automatic transmission with 4 forward and 2 reverse gears. The Desert AS90 features enhanced engine, transmission oil and auxiliary power unit cooling systems and also a Diehl 940 pin track for better handling in sandy terrain.

The vehicle can traverse gradients up to 60%, vertical obstacles to 0.75 m, and trenches to a width of 2.8 m, and is able to ford water to a depth of 1.5 m.