The Bofors 40L70 is an automatic 40mm anti-aircraft gun, developed by the Swedish company, Bofors, in the late 1940s, and which continues to be in service in a significant number of countries, in its naval and military versions. terrestrial, although, at present, the original manufacturer has discontinued the manufacture and maintenance of these assemblies.
Because of their long service life, there are serious problems of obsolescence of components for their maintenance, especially in regard to control electronics and servo systems. However, Navantia Systems regularly detects business opportunities related to this weapon, such as maintenance programs associated with ship modernization opportunities, in different countries that own Bofors 40L70 assemblies, which are difficult to meet due to the difficulty in acquiring the necessary spare parts.
This circumstance led to the achievement of this R & D program that would allow us to access the market covering these business opportunities, while experimenting with new solutions that may be applied, in the future, to some systems products.
Targets aimed at commercialization
The FT R & D program, which began in mid-2014 and has been executed by a team consisting entirely of people from Navantia Systems, was completed in December of last year as planned with satisfactory results obtained during the evaluation tests carried out in the prototype built on a mount given off by the Spanish Navy.
The monitoring of the same, according to our internal procedures, was made based on Technical Meetings of Advance of the program (TMA) that counted on the presence of external observers, naval weapons engineers of the Spanish Navy.
The objectives established at the beginning of the program, pointed to the development, manufacture of the prototype (using a discharged cannon in the Spanish Navy) and evaluation tests in the workshop of a new local command and distance for these artillery assemblies with very definite direct benefits. :
- Have a solution that allows opting for overhaul and maintenance contracts
- Solve the current problems of obsolescence with the maximum guarantees
- Facilitate the integration of the 40L70 assemblies with the family of Dorna fire directions, another Systems product, in future vessel modernization contracts
As an additional specification, and in order to simplify as much as possible the implementation of modernization in the systems in service, it was established that the new components of the development were housed in the existing compartments of the old gun control electronics.
A consistent technical solution
The design of the new control system has consisted of replacing all the old electronics of the barrel, analog and very obsolete, by a last generation system based on an Intel COM-Express processor card (Intel Core i7 processor).
The software (GMCP or Gun Mount Control Process), which runs in a Linux operating environment, has been developed specifically for this program and includes all the necessary process modules for the interface with the external firing direction, interface with the signals of the own cannon, calculations with their own algorithms and effective control of the servos. It also has a module for simulating the behavior of the assembly and an external control unit, which have been used in some phases of development, and could be exploited in the future for maintenance and adestration operations.
For the communication of the process system with the signals of the barrel, interface cards have been designed for the lower support (fixed part) and the upper part (mobile part) of the assembly, communicated with each other by a high-speed serial line through the ring original collector of the cannon. In order to facilitate the implementation of modernization these cards receive information or send orders directly to the original sensors and actuators of the assembly, but in its development have also included inputs and outputs of various types to ensure future growth, so that they can substitute other obsolete elements of the gun for last generation units without impact on the installed electronics.
The new electronics acts on the hydraulic control of the assembly, thus maintaining the original hydraulic functionality, but a study has been made for the possible replacement of this system by electric motors, which would allow to increase the maintainability of the guns. This study has reached a high degree of maturity with the selection, even of specific motors and clutches of the market, although it has not been possible to include in the current program the manufacture of a prototype and the characterization of the system.
Regarding the remote control from an external firing direction, the original configuration has been maintained, which allows the positioning and control of the assembly by means of a set of synchronous and discrete signals, but a data interface has also been implemented, through the network Redundant Ethernet, for connection to more modern draft directions, such as those belonging to the family of Dorna shooting directions, developed by Navantia Systems.
Direct benefits and new knowledge acquired
The finalization of the development last year and the results of the evaluation tests have allowed, immediately, the launch of offers of modernization of assemblies Bofors 40L70 for countries that have these guns in service, offering the implementation of the modernization in a while of very short work and minimal impact on the current configuration of the ships. It is interesting to note that, during the execution of the program, clients with interest in modernization have been identified, such as Morocco, Bahrain or Egypt.
Having this solution will allow, in the very near future, to extend the commercial action to other potential customers by offering them an opportunity to improve the maintainability of their systems or, together with the supply of the Dorna shooting direction, in any of its versions, to constitute one more work package to be offered for the modernization of ships in service.
In addition to this direct benefit, the new knowledge acquired during the development of the modernization are already available for use in other Systems products. Among them:
- Control of servo valves with current loop
- Adaptation of Control Transformers for conversion in synchronous
- Self-generated 400Hz reference signal module
- Creation of a new simulation and maintenance tool, specific for the assembly, but adaptable to the control of other servo tehcnical systems