The 155mm 52Cal Artillery Truck Mounted Gun Howitzer, known as the ATMOS 2000, is a new product based on the "Rascal". The ATMOS 2000 is an advanced concept of long range, light self propelled wheeled artillery system, with ammunition loading systems and autonomous operation capabilities.

The ATMOS 2000 is a hybrid of the TATRA T815 VVN 6X6 wheeled Truck chassis, with Soltam made 155 mm 45/52 Cal Long-Range Gun (ATHOS) that is equipped with the most modern c3 system including on board computation, Inertial Navigation & Aiming Systems, and easy ammunition handling system. The platform carries 32 projectiles and propelling charges, as well as the Guns crewmembers, their equipment and all the logistics. While firing, the ATMOS 2000 is supported by rear spades. Firing loads are transferred directly to the ground, without harming the vehicle chassis.

This system can mount either 45 cal. Barrel, or 52 cal. Barrel to reach 39 km or 41 km respectively. All types of 155 mm Ammunition, in use worldwide are authorized for fire. The auxilliary engine enables easy handling for deployment and ammunition handling. As a result, the ATMOS 2000 is fully operable by 4 crew members.

The SP Gun is equipped with Inertial Navigation and Aiming systems, which commands and controls also the elevation & traversing gears, giving the ATMOS 2000 autonomous operation and "automatic laying" capabilities. It has a total weight of 18000 kg.

Late in 2001, Soltam Systems released details of the latest version of its ATMOS (Autonomous Truck MOunted howitzer System) 2000 155 mm/52 calibre self-propelled artillery system whose existence was first revealed late in 1999. At that time it was also referred to as the 155 mm Self-Propelled Wheeled Gun (SPWG).

ATMOS 2000 has been developed by Soltam Systems as a private venture. It is aimed mainly at the export market, although it has already been demonstrated to the Israel Defence Force.

There are nine subcontractors to Soltam Systems on the ATMOS 2000 programme, including SAGEM of France.

According to Soltam Systems, wheeled self-propelled guns are not only cheaper to procure than their more common tracked counterparts, but have lower life cycle costs and are easier to operate and maintain.

In addition they also have greater strategic mobility as they do not have to rely on Heavy Equipment Transporters (HETs) to be redeployed over extended distances as do their full-tracked counterparts.

By late 2001 the prototype ATMOS 2000 fired over 1,000 rounds of various natures of 155 mm ammunition, using bagged charges during extensive company trials in Israel.

In mid-2003 it was revealed that an undisclosed export customer had placed a contract with the company worth USD5 million for an undisclosed batch of ATMOS 2000 systems.

From late 2004 the Israel Defence Force (IDF) carried out extensive field tests on the locally developed Soltam Systems ATMOS 155 mm/52 calibre self-propelled (SP) artillery system.

Today the mainstay of the IDF field artillery is the US-supplied BAE Systems, Ground Systems, M109A2/A3 155 mm SP howitzer, which is called the Doher. This has been modified in a number of areas and has a 155 mm/39 calibre ordnance and an upgraded onboard fire-control system.

Funding permitting, the Israel Defence Force (IDF) is expected to order an initial batch of 18 Soltam Systems ATMOS that will be sufficient to form one artillery regiment with three batteries each with six weapons.

The IDF is expected to complete an exhaustive series of firepower and mobility trials with a prototype ATMOS system in 2007/2008. For the export market, Soltam Systems is currently marketing ATMOS with 155 mm 39, 45 and 52 calibre barrels.

It is understood that the IDF will opt for a 155 mm/39 calibre system as this will have the same ballistics as the US-supplied now BAE Systems, Ground Systems, M109A2/A3 Doher self-propelled howitzers (SPH) used in large numbers by the IDF.

To further save costs, it is also understood that the IDF ATMOS will use the elevating mass and 155 mm/39 calibre ordnance taken from its existing in-service Soltam Systems towed artillery systems.

The IDF ATMOS 155 mm/39 systems will be integrated onto the rear of a US-supplied American Truck Company (6×6) high-mobility truck chassis which will be procured using Foreign Military Sales (FMS) funding.

Under a deal signed late in 2004, the IDF has already taken delivery of over 300 American Truck Company (6×6) trucks. This company is a joint venture between Tatra of the Czech Republic and the US Terex Corporation. This truck is based on the Tatra T815 forward control truck that is marketed in a wide range of configurations.

According to Soltam Systems several undisclosed export customers have already placed orders for the ATMOS 2000 system. According to the United Nations, recent export sales by Soltam Systems of 155 mm towed artillery systems have included Cameroon (18), India (60), Slovenia (18) and Uganda (18).

The Soltam Systems ATMOS, 155 mm/52 calibre self-propelled artillery system essentially consists of a 6 × 6 cross-country truck chassis, on the rear of which is mounted the upper part of a Soltam Systems 155 mm/52 calibre towed TIG 2000 system.

The prototype is fitted with a 155 mm/52 calibre ordnance that conforms to the NATO Joint Ballistic Memorandum of Understanding (JBMoU), although Soltam Systems 155 mm/39 and 155 mm/45 calibre barrels can also be fitted.

The breech mechanism is of the horizontal sliding type and automatically opens to the right with self sealing metal obturating rings.

The buffer is of the one cylinder hydraulic type with the recuperator being of the hydropneumatic type. Recoil length is variable from 850 to 1,100 mm. Two pneumatic equilibrators are fitted.

Weapon elevation and traverse is all hydraulic and computer controlled. The hydraulic power pack operates the howitzer's aiming gears as well as the load assist systems and spades.

When fitted with a 155 mm/52 calibre barrel, a maximum range of 41 km can be obtained firing an Extended Range Full-Bore - Base Bleed (ERFB-BB) projectile, 30 km firing the NATO L15 High Explosive (HE) projectile and 24.5 km firing the older M107 HE projectile.

ATMOS 2000 carries a total of 32 155 mm projectiles and associated charges and is normally operated by a crew of four, of whom two are loaders positioned one either side at the rear.

A rate of fire of between 4 and 9 rds/min are claimed and to reduce crew fatigue, a flick rammer is fitted as standard. To provide a more stable firing platform, two large spades are lowered to the ground one either side at the rear of the system by remote hydraulic control.

It also has an onboard Advanced Fire-Control System (AFCS). This includes a main computer and a navigation and aiming device and enables ATMOS 2000 to rapidly engage the target after receiving the position of the target from the Forward Observation Officer (FOO).

The AFCS processes the target information, presents this on a display to the gunner and then lays the weapon onto the target in traverse and elevation. Manual back-up is also provided for in case of power failure.

Although the prototype system is installed on a modified Tatra (6 × 6) truck chassis (which has been built under licence in India), Soltam Systems have emphasised that it could be fitted to a wider range of other tracked and wheeled chassis.

The forward-control armour-protected cab provides the occupants with protection from small arms fire and shell splinters. It is envisioned that production versions of the ATMOS 2000 would be fully air-portable in a Lockheed Martin C-130 Hercules transport aircraft.

• ATMOS 2000 155 mm M46S

Soltam Systems have stated that the ATMOS 2000 could be fitted with the saddle and elevating mass of the Russian 130 mm M-46 field gun, with the ordnance replaced by a new 155 mm/45 calibre system.

Soltam Systems has already won a major contract from India to upgrade some 180 Russian-supplied 130 mm M-46 field guns with a 155 mm/39 calibre and 155 mm/45 calibre ordnance in 2000.

Recent information has indicated that the first production lot of ATMOS systems for an unidentified export customer may well be based on the elevation mass of the Russian 130 mm M-46 but fitted with a new 155 mm ordnance.