AUF2 GCT - Grande Cadence de Tir
In 1999 Giat Industries was awarded a combined development and production contract from the Delegation General pour I'Armement (DGA) to upgrade at least part of the French Army's fleet of 155 mm GCT (or AUF1) self-propelled artillery systems to extend their operational lives into the 21st century. In 2003, in connection with the adoption of the 155-mm CAESAR self-propelled howitzer, it was decided not to upgrade the AUF1 self-propelled howitzer to the AUF2 level.
The turret was to stripped down and refurbished and an automatic gun laying system befitted. The chassis also was to be refurbished and the current powerpack consisting of a Hispano Suiza HS 110 12-cylinder engine coupled to a mechanical transmission was to be replaced by a new powerpack consisting of a Renault Mack E9 series diesel coupled to a new ENC 200 transmission. The suspension was also to be upgraded for improved cross-country mobility. According to Giat Industries, some 80 percent of the maintenance requirement for the French Army GCT is in the chassis. The exact number of systems to be upgraded was not initially decided but the first batch would have consisted of 70 units with the second batch expected to consist of 104 units. When upgraded they were to be designated the AUF2.
The most significant difference of SG AUF2 from the previous options is the installation of a barrel with a length of 52 klb and a charging chamber with a volume of 23 liters. The maximum firing range of an active-missile projectile (APC) NR265 is 42 km. According to the representative of the company "Giat", the cradle of SG AUF2 will have the smallest weight and size characteristics among the devices of this class. The substantial upgrade to the GCT will include the installation of a new 155 mm 52 calibre ordnance fitted with a new screw type breech mechanism, double baffle muzzle brake and a modified recoil system. A new modular charge system was developed by Giat Industries and firing an extended range full bore - base bleed projectile a maximum range of 40 km was achieved.
In order to reduce the recoil force and prevent the maximum allowed recoil length to be exceeded, a new muzzle brake is being developed, the effectiveness of which, according to the developers, reaches 45 percent, while the existing one has only 30 percent. Another important element in improving the fire fighting system is reducing the size of parts of the artillery unit, especially the wedge of the bolt, muzzle brake and recoil devices. A new, lighter and more compact, piston gate wedge will be equipped with an automatic ignition system of the powder charge and have a single drive for the opening and closing mechanisms. The minimum dimensions that the components of the artillery unit must have will be finally approved during the testing of various variants of the recoil systems and measuring the force of interaction of parts (strength, position, inertia, etc.), as well as taking into account the internal ballistics. As a result of research of various design options for the muzzle brake, the possibility of lateral movement of the barrel during a shot will be almost completely excluded.
New to artillery systems is the hydropneumatic system of braking recoil. The principle of operation is based on the quenching of the recoil energy by transferring it to the compressed nitrogen placed in the tank inside the recoil devices. This energy will be used to actuate the gate wedge and projectile feed mechanism. Its value depends on the angle of elevation of the barrel, which ensures a safe firing and prevent excessive pressure on the elements of the shot.
The standard non-chromium SG barrel AUF1 T with a system of propellant charges in hard burning cards is designed to produce 4,000 shots. In accordance with the memorandum, the AUF2 barrel for SG should withstand 2,000 shots on the sixth charge, consisting of the six elements of the set of modular propellant charges (MMW) TCM. This set of MMP is intended for the formation of charges from the third to the sixth. However, it is expected that the SG AUF2 base barrel with a full thin wear-resistant coating used in CAESAR SG will be designed for 2,000 LU211 CFC shots on the fifth charge and 500-1,000 shots on the sixth.
In contrast to the American and German artillery barrels of French production have a thicker coating at the combustion chamber than the muzzle brake. During the implementation of the ADVITAR program, several hundred shots were fired and, according to the representatives of the Directorate, satisfactory results were achieved in reducing the erosion of the bore. During the tests, the equipment used to measure the wear of the barrel bore, developed under the auspices of the DGA Directorate.
The patented system for measuring the temperature of the walls of the bore was used to determine the parameters of the trunk for SG AUF2. Temperature sensors were located at a distance of 2 mm from the inner wall of the trunk. The data from the sensors can be transmitted to the ATLAS automated control system computer at the battery command center in real time.
The maximum rate of fire of the AUF1T SG is three shots in 15 seconds, the practical one is six shots in 50 seconds, the rate of fire during continuous shooting is 72 shots / h. On test firing, the crew of one gun carried out 108 shots within an hour. For SG AUF2, experts expect similar parameters of fire rate, but it is possible to increase the practical rate of fire up to 10 shots / mini to realize the almost simultaneous delivery of several projectiles fired from one gun to the target area. It is assumed that in 14 s at a distance of 10 to 25 km, 8-10 shells will be delivered.
The automatic loader (A3), designed for SG AUF2, was designed to function with the MMZ. The shop is divided into two parts. In the left part of the tower 180 modules MZ are placed, in the right - 42 projectiles. A3 consists of a magazine with cells, bracket, conveyor, inclined plate, auxiliary pallet and pusher.
Each cell contains six TCM modules. The conveyor, which slides along the bracket, picks up the modules from one cell and delivers them to the inclined plate with which they roll onto the auxiliary pallet. Next, the pusher lever according to the signals of the automated process control system selects the required number of modules, first they fall on the pusher pallet, and then they are fed into the combustion chamber, after which the shot occurs. The modules remaining on the auxiliary pallet are used for the next shot. The proposed automatic loader forms a charge consisting of modules of the same type.
The GCT Howitzer Turret armor protects three crew members from shell fragments, small arms ammunition in all directions, as well as against 12.7 mm ammunition in the forward hemisphere. Additional means of protection are launchers for the automatic ejection of grenades with smoke screens that are located on the front side of the tower. The impact of the damaging factors of nuclear, chemical and bacteriological weapons is hampered by the sealing of the door, filtering devices and the maintenance of excessive pressure inside the tower and the hull.
France as the chassis for SG AUF2 decided to use the chassis of the AMX-30 B2, but the turret can be placed on the chassis of the other MBT. In the 1970s, the chassis for the GCT howitzers was performed by the undercarriage of the Leopard 1 MBT. For India, the option of installing the GCT turret on the chassis of a T-72M1 tank, produced in the country under a Russian license, and the Indian Arjun tank was considered. For France the SG AUF2 would be on the chassis of the French Leclerc tank. In this case, the diesel engine V8X-15OO "Hyperbar" capacity of 1,500 liters would provide a specific power of 33 liters. s / t, which may seem redundant, but it, according to the doctrine of the Great Britain of France, will satisfy the mobility requirements for armored formations. It would also increase the possibility of active defense against attacks from above, below, from the flanks.
It was planned to complete the creation of prototypes of SG AUF1 and TA AUF2 in June 2002, shooting of SG AUF2 in December 2002, qualification tests in 2003, and the production of the first batch in 2004. Production of SG GCT for national CBs could have been completed in 2008. The modernization of the self-propelled artillery fleet of the armed forces of France, according to French experts, would make it possible to bring artillery systems in service to a level that meets modern requirements and extend their service life by 20 years.
The end of the Cold War led to a significant reduction in the number of French ground forces and, consequently, artillery units. In addition, the first war in the Persian Gulf (1990-1991) marked a change in priorities in the construction of the armed forces. Now, instead of confronting Soviet tanks in Europe, operations in Asia and Africa came to the fore, which required not “heavy” armored formations, but mobile units for rapid response. ACS AUF2, due to its size and weight, precluding airborne transport, was not suitable for such tasks, which was the reason for the termination of purchases of heavy self-propelled guns.
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