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AMX Leclerc - Main battle tank for the year 2000

Written by Sakhal

Coming from GIAT (Groupement Industriel des Armaments Terrestres), the AMX Leclerc is the latest French development of a main battle tank, destined to serve with the French Army from the 1990s. At that time it should replace the AMX-30B2, which had to remain in service without modifications until the end of the century. In 1987 France was seeking foreign partners for its national program, to be able to fulfill the order of 1400 tanks of this type for the French Army.

When the AMX Leclerc was presented to the specialized press the 15th January 1987, the Ministry of Defense had to answer a series of questions, such as:

- Will the AMX Leclerc really represent a new generation of main battle tanks, regarding the evolution of this kind of vehicles during the next decades and their defense against antitank weapons, helicopters and nuclear, biological, chemical or electronic threats?

- Will it be possible to complete within the deadline set the AMX Leclerc program, to which more than 35 billions of francs had been dedicated during the former year?

- Should the AMX Leclerc and AMX-40 be considered competitors regarding both the exportation market and the incorporation to the French Army?

AMX Leclerc - Main battle tank for the year 2000

According to declarations from those responsible of the program, the answer to the first two questions was a sound "yes", while the answer to the third question was an equally sound "no", as the AMX Leclerc and the AMX-40 were not competitors of each other. Both programs, with very different deadlines, were the result of two totally different conceptions. The AMX Leclerc was conceived as a response to military requirements from the French Army and was a totally national project, which however did not exclude the possibility of a cooperation program. On the other hand, the AMX-40 was devised, from the beginning, for the exportation market, and its characteristics and prestations were defined by its manufacturer, GIAT, based on requisites from potential customers. The AMX-40 was adapted to countries with desertic and hot climates, being carried out its most significant evaluations in Abu Dhabi (United Arab Emirates), Djibouti, Katar and - in a longer cycle - Saudi Arabia. Besides, GIAT had the intention to offer the AMX-40 as a base tank for other customers that required modifications, which would be easy to accomplish with this tank. It was a rather rustic vehicle whose price was somewhere between that of the AMX-30B2 and that of the German Leopard 2 and which, being in preseries stage in 1987, was intented to enter serial production within two years. It is indubitable that, specially regarding its armament, the AMX-40 benefited from some elements that were parallely developed for the AMX Leclerc; however both tanks had a different past and present and their future should not cross.

AMX Leclerc - Main battle tank for the year 2000

Since no foreign customers could be attracted, from 1990 the AMX-40 no longer was offered for exportation.

Independently of the doubts that were formulated in respect of the AMX Leclerc program during the elaboration of the French defense budget of 1987-1993, the whole investigation work continued during 1986. The hull with the experimental wheel chassis, predecessor of the definitive one, was submitted to different evaluation tests in the diverse test centers operated by GIAT, and the third prototype had received on the last summer its complete turret fitted with all the prototype elements: electric stabilizators, main weapon and fire director, laser rangefinder, command and sight devices, etc... It was a totally functional prototype which could be tested on the Sensor Test Center located in Landes, where the first firing tests were carried out. This very brief phase of the evaluation was carried out along with simultaneous evaluations in the CELAR (Centre d'Electronique de l'Armement) located in Bruz, where since six months ago was operating a simulator which allowed to recreate every possible movement of the turret as well as the audiovisual environment required to evaluate each of the operational areas (setup of the diverse acquisition systems, integration of navigational means, target designation systems, communication between crew positions, firing process, etc...) The turret which could be seen in the presentation at Satory was not very different from the original one, at least once all the experimentation devices (also known as "onboard spies") were removed from it.

AMX Leclerc - Main battle tank for the year 2000

The functional prototype of the AMX Leclerc in the Satory test field shows some resemblance with the external appearance of the German main battle tank Leopard 2.

The general physiognomy of the AMX Leclerc had been already established, but the suspension was still a matter to solve. The first trials with the experimental wheel chassis were made with a long- stroke torsion bar suspension, but shortly later tests of an hydropneumatic suspension were started on an experimental chassis denominated VEDYS, which would allow its dynamical evaluation without altering the deadlines set on the program. From the beginning important decisions were taken regarding a Diesel 1500-horsepower engine, an automatic cannon loader and a flat turret for two crew members, with electric rotation. All of this gave as result a rather complex assembly composed of subsystems interlinked by a digital databus. Later, the tank would receive a radio fitted with frequency hopping properties, which was still in development and which should allow secure transmission and reception of any kind of operational information in the environment of electronic war expected for the year 2000.

The next significant phase started in 1989, when the six preseries prototypes that would open the way to the industrial phase were delivered. Following the program set, the assembly line should deliver the first series tank in the late 1991. The cost of the program (including ammunitions) had been set in 35 millions of francs in the early 1986, of which 22 millions corresponded to the tank itself. These expenses were highly monitored by the Chief Staff of the Army, which in no way wanted to be dragged by investigations about maximum prestations. To be used effectively, the units equipped with the AMX Leclerc would require the appropriate support from helicopters, artillery, multiple rocket launchers, infantry, sappers and of course its own logistic system. Thus, the investigation of the coherency and complementarity of the diverse systems of the Armed Forces is a permanent task of the Chief Staff.

AMX Leclerc - Main battle tank for the year 2000

AMX Leclerc - Main battle tank for the year 2000

Electronic command of the turret

For handling the turret, the AMX Leclerc has in its center a box with a BEA (Boiter Electronique d'Asservissement) command electronic computer, developed by French company Alcatel CGA-HBS (Compagnie Generale d'Automatisme), which assumes the following functions:

- Command of the turret and the main weapon for an effective firing while the tank is in movement. To be able to perform this function, the BEA receives information from different sensors which, after being processed by a Kalman filter and preprogrammed parameters, delivers orders to the servomotors with the purpose of stabilizing the main weapon.

- Direction of the ensemble of connected sensors and of an energy generation subsystem. Retransmission, through a high-cadence serial digital databus, of the status of the aiming subsystem to the processor of the fire director, which handles the turret.

- In the event of failure on the computer of the fire director, the BEA takes control of the turret assuming the handling of the digital databus, managing a certain number of components that are indispensable for firing while in movement without diminishing the effectiveness of the main weapon.

- In the event of failure on the numeric control of the BEA, an emergency circuit is established which is enough to control the safety devices of the mechanical structure.

To be able to perform the aforementioned functions, the BEA has a certain number of printed circuit boards housed inside an hermetically closed metallic box. The linking with the sensors and other peripheral devices is made through external interfaces by means of HE 308-type connectors. The central unit of the BEA is based in a 68020-type 16.67 MHz microprocessor, contained in a REPROM (Reprogrammable Read-Only Memory). When turned on, the program is loaded in some 70-nanosecond RAM (Random Access Memory) which allow its execution in a minimal time without a waiting cycle, as the 68020 offers a small access time to memory. The central unit has also an EPROM (Eraseable Programmable Read-Only Memory) allowing the conversion between values that are characteristic and susceptible to modifications and between those that must protect each other while under tension. An additional 68881-type processor allows computation with floating comma. There are two serially connected lines for dialogue with a console, introduction of the program, information exchange with another equipment, etc...

It has been chosen a simplified VME-type data microbus. The BEA allows the following input-output functions:

Analogue informations:

- 16 analogue outputs differentially transmitted with a resolution of 16 bits and a precision of 14 bits. A low-pass filter with regulable output allows to partially suppress transmission noises. The totality of informations is galvanically isolated (1500 volts) from the computer part.

- A digital-analogue conversion card allows, after the galvanic isolation, four different outputs with a precision of 12 bits.

- A digital resolution conversion card allows to obtain two resolutions with a precision of 14 bits.

Logic informations:

- 16 inputs and 16 outputs of single channel, with galvanic isolation, allow to retransmit values such as tops, stops, blocks, etc...


This function, effectuated by means of a fully analogue card, fed by its own converter, allows to move the turret without having to stop monitoring the mechanical structure.

All of the analogue and digital inputs-outputs are controlled by the computer. The printed circuit boards are conceived in such a way that in the event of failure it can be ascertainedwhether it comes from the BEA or otherwise is unrelated to it (a revision corresponding to the second level of maintenance).

AMX Leclerc - Main battle tank for the year 2000

Optronic elements

The tremendous complexity of modern optronics is well represented by the family of electronic sights developed by French company SAGEM, which created the VTI (Viseur Tireur Integre) system for the AMX Leclerc. The VTI served as base for the SAVAN family. Its precise stabilized line of sight allows to use it from moving vehicles. The VTI - like the SAVAN 20 - has three subsystems: stabilized sight head, target tracking device and digital electronic unit. The sight head has two windows, one for the diurnal channel and another one for the thermal image camera, incorporating a large mirror made of light alloy based on beryllium, of low inertia and great mechanical stability, providing good stabilization of the image in both the visible and the low-high infrared spectrums. Mounted in a universal joint, it is stabilized in two axes by two gyroscopes and an accelerometer, while the movement is transmitted by a transmission belt. The system allows to stabilize the line of sight with a precision of about 50 milliradian.

A second gyroscope and another two accelerometers serve as an optional system for vertical and navigational reference, without having to check the magnetic North. For navigation, the inertial platform can be supplemented with an odometer connected to the propulsion plant for measuring the distance covered. Successive readjustments of the points stored in memory, at the beginning of a mission, are made with a precision of around 1 percent. This function allows each tank to be controlled from a centralized command post, such as the SIR (Sisteme Informatique Regimentaire). The mounting for target tracking consists of several elements, according to user choice. In the case of the HL-60 gunner's sight it can include: eyepiece for the gunner, television displays, infrared and CCD (Charge Coupled Device) cameras, a Nd-YAG laser and a symbol generator. The diurnal channel serves simultaneously to the eyepiece, to the television camera and to the laser with a separating prism walled between them.

The digital electronic unit is one of modular design. The card interfaces provide a link for the DIGIBUS (in the HL-60) or the DATABUS 1553 (of American origin). The processors (three of 68000 type in the HL-60, programmed in Pascal language) control the relation between the weapons systems and the components of the sight. The computerized electronic unit determines the angular position relative to the target, the absolute angular speed and the speed, with a precision of 0.1 milliradian or less. Since the cannon is linked to the gunner's sight by the aiming controls and the stabilization of the line of sight, the gunner's sight continuously delivers data of the turret and a vertical reference to the cannon. The HL-60 of the AMX Leclerc is installed to the right of the cannon and has three optical channels: diurnal channel with CCD television camera, nocturnal channel with thermal image camera and laser rangefinder channel. All the three use the same mirror, which is stabilized in both elevation and azimuth. An interface allows to transfer to the presentation display of the tank's commander the images taken by the HL-60, which curiously has as well a stadiametric scale.

The SAVAN 10, built for exportation, differs from the HL-60 and SAVAN 20 in that it lacks a thermal image camera. The size of the sight head is smaller (135x300x300 millimeters), it has a single window and a 70-millimeter lens for diurnal vision, through which the laser beam passes by. Other than that, it has the same functions of the other systems including the vertical and navigational reference, the performance characteristics regarding stabilization of the line of sight, navigation, aiming precision and speed (1 radian/second) and aiming acceleration (15 radians/second squared).

AMX Leclerc - Main battle tank for the year 2000

Upper picture: gyro-stabilized aiming system developed by SAGEM for the gunner of the AMX Leclerc. Lower picture: another development by SAGEM is the gyro-stabilized modular periscope VIGY 40, for observation and aiming, with incorporated laser rangefinder, being possible the installation of either a thermal image camera or a starlight intensifier.

SAGEM also manufactures the VS 580 tank's commander sight used by the British main battle tank Challenger 2. The VS 580 has a panoramic stabilized sight head, an intermediate mounting and an electronic unit. The sight head, identical in every model, has a x2, x3.2 and x10.5 magnification system, plus a mirror mounted in a universal joint, stabilized by a miniaturized two-axis gyroscopic tuner, coupled to an analyzer sensor that provides angular data. The intermediate mounting, according to user choice, integrates several elements, a laser rangefinder and a starlight intensifier. The telescopic mounting comprises lenses, eyepiece with adjustable dioptrias, fixed prism for image correction (with five reflections to shorten the optical path), photo-optical retractable filter and protective filter for laser emissions and brightness control.

While moving in rugged terrain, the VS 580 provides a stabilized line of sight with a precision of 0.2 milliradian, allowing to spot targets at 4600 meters and to identify them at 2600 meters. It is believed that this sight grants a 90 percent probability of accurate impact at the first shot with APFSDS ammunition against a target at 1500 meters, with the probability falling to 30 percent at 2500 meters. These results are comparable to those achieved by the gunner's sight. On the AMX Leclerc the commander has at his disposal the HL-15 sight (manufactured by SAGEM as well) providing diurnal channel with x2, x2.5 and x10 magnification, nocturnal channel with a third-generation starlight intensifier and laser rangefinder channel.

Article updated: 2017-12-24

Categories: Tanks - Engineering - 20th Century - 21st Century - [General]


Website: Military History

Article submitted: 2017-12-24

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