Computer history LEOK: background on the Mech Lua Trainer


Computer history LEOK: Background on the Mech Lua Trainer

Source: “The Netherlands AA Tank Training System”, Publication 1/1980 by HSA B.V. and LEOK-TNO

The 35 mm AA Tank CAESAR: Introduction

MLT leaflet cover
MLT leaflet cover

In 1971, the Netherlands Army acquired five 35 mm Anti-Aircraft tank PRTL systems for experimenting. In 1973, after many experiments, an order for 60 PRTLs followed. Another 35 systems were ordered in 1974. In addition, munition, maintenance material, spare parts, etceteras. In total, a cost of 1.4 billion Dutch Guiders.
With the introduction of the 35 mm Anti-Aircraft tank, type CA-1 (CAESAR) between 1977-1979, the Netherlands Army had the disposal of a modern and sophisticated weapon system. The Caesar system was developed based on Netherlands military requirements for an armoured vehicle equipped with a proven AA weapon coupled to a highly effective radar fire control system and capable of keeping pace with other armoured units on the battlefield.
Oerlikon-Contraves, Hollandse Signaalapparaten and Kraus Maffei jointly developed the CA-1 weapon system.

The AA tank fills the gap in the defence against low-flying aircraft. The weapon system, mounted on a Leopard 1 battle tank chassis, is fully autonomous, its main components being:

  • a search and tracking radar,
  • two periscopes,
  • fire control system with an analogue computer, and
  • a 35 mm twin gun.

The AA tank has a crew of three men: the commander, the gunner and the driver:

  • The commander is in charge of the tactical use of the weapon system. He evaluates the air threat, decides about target engagement, and maintains radio communication.
  • The gunner is charged with the engagement of the target selected, using the optimum mode of operation. If necessary, a single operator can execute an engagement and operate the entire weapon system.
  • The driver manoeuvres the AA tank as ordered by the commander.
AA a.k.a. Pantser Rups Tegen Luchtdoelen (PRTL); nicknamed Pruttel
AA a.k.a. Pantser Rups Tegen Luchtdoelen (PRTL); nicknamed Pruttel


Pantser Rups Tegen Luchtdoelen (PRTL); nicknamed Pruttel
Pantser Rups Tegen Luchtdoelen (PRTL); nicknamed Pruttel

The X-band search radar continuously scans the surrounding airspace, no matter whether the vehicle is at a standstill or on the move. In the MTI mode of operation, only moving targets are displayed on the radar screen. Each target displayed is automatically interrogated for its identity (friend or foe).

The commander selects the target to be engaged by marking the echo and presses a button for automatic acquisition and tracking of the target by the X-band/Ka-band tracking radar, whilst air surveillance by the search radar will continue without interruption.

The commander and gunner have a periscope at their disposal. These are used in the optical mode of ground and air target acquisition and tracking, and combat zone observation.

The fire control system aims the guns, taking into account the continuously measured target data, the meteorological data, and the muzzle velocity. As soon as the target is within the effective range, the operator receives the “Ready for Firing” indication.

More background information in Dutch on the PRTL can be found here.

Mech Lua trainer (MLT)
Mech Lua Trainer (MLT)
De Ferranti computerrekken
The Ferranti computer racks


Instructor console


Contour image

In September 1970, the LEOK received the assignment to carry out a study into the possibilities of realising a trainer for a mechanised Anti-Air Artillery-weapon system. This led to the development of a successful trainer program. Together with Hollandse Signaal Apparaten (HSA), the development of the ‘Mech Lua Trainer’ (or PLT) described above started in the mid-1970s. The system was delivered to the Royal Netherlands Army. With the trainer, it was possible to train three teams of a commander and a shooter with functions such as goal evaluation, acquisition and tracking. Synthetic radar and periscope images were correlated. The simulation of the noise from the artillery tower and electronic countermeasures was part of the simulation program.

The system consisted of three subsystems: a weapons system simulator, a combat field simulation, and facilities for the instructor. With the construction of this trainer, TNO acquired knowledge of Computer Aided Instruction (CAI) and Computer Supporting Education in training simulators. The CAI activities led to the development of a universally applicable modular CAI system. That CAI system could be connected to a variety of real-time simulators. It could serve both for preparing training scenarios and for taking over much of the diagnosis of the student’s results during the training. Therefore, the CAI system consisted of two main modules: a preparation module and a training module.

A special microprocessor system was developed, the LMP

The operational mobile anti-aircraft artillery system PRTL showed a degree of ‘commonality’ with the German Gepard system. A mid-life update program was planned for both weapon systems at the end of the 1980s. In the framework of the collaboration between the German and Dutch Army and the possibility of joint use of the weapon systems, it was decided to implement the update program bilaterally including the training simulators for the Dutch PLT-V, (PLT-Improved). After all, the CAI in the PLT was delivered 15 years earlier by the LEOK. This CAI was still functioning satisfactorily.

For that reason, TNO-FEL was also asked to develop the CAI for the PLT-V. A consortium consisting of main contractor Krauss-Maffei München, Deutsche System Technik (DST) Bremen, Hydraudyne Boxtel and TNO-FEL worked on the development of the new trainer. On the government side, the Bundesamt für Wehrtechnik und Beschaffung in Koblenz (BWB) was the client on behalf of Germany and the Netherlands.
At the end of 1994, the TNO-FEL development was successfully concluded by means of Factory Acceptance Tests. In 1995, the subsystems of the various partners were integrated into a total system consisting of a Dutch and a German simulator and one instructor station. This total system has been tested by the Dutch and German schools, whereby the outcomes and the experiences gained during the research have been incorporated into the final specifications for the series construction. The research period was concluded positively by the end-user. In 1996, the order for the series of training units was placed with a planned delivery in 1998.

In line with expectations, the CAI has shown that the training system has taken a big step forward in the field of automatic (objective!) Assessment and lesson progress, user-friendliness and instructor support. Although at the start of the project at the German school some reserve existed regarding the modern Dutch training philosophy which is an integral part of the CAI, a positive attitude was later observed. Thanks to the realization of this trainer, another step forward was taken in the context of German-Dutch cooperation.