Vehicle ballistic armour - M113 Armoured Personnel Carrier

The M113 Armoured Personnel Carrier is one of the most used military vehicles in the world, with some 80 000 in service with 47 nations, spread across five continents.

The development, manufacture and use of these vehicles started more than 30 years ago. Since few countries are contemplating a general change-over, upgrading existing vehicles to provide extension of useful life by adapting the vehicle to present day technical requirements, is being undertaken. This affects, amongst other things, the drive-line, steering and braking systems and present armament of the vehicle. The most important point, however, is protection for soldiers. Since enormous advances have been made in weapons technology in the course of time, one can well imagine that the threat to vehicles has also become greater and their protection must therefore be increased.

To protect those travelling in the personnel carrier more effectively against penetrating fire and the associated hazard of secondary splintering, so-called spall liners are fitted to the inside of the vehicle.

As this vehicle was developed and produced many years ago, it will be clear that it was not designed to assume high additional weights. Increased protection through the use of 'ballistic steel' as the traditional armouring material is out of the question. Moreover, this material itself again splinters on penetrating fire. As the splinters are generally released at an angle of up to 120 degrees into the inside of the vehicle, they constitute an enormous threat to the occupants. The Australian army consequently decided, as a first step, to fit the M 113 with a spall liner.

After the solutions existing on the world market had been analyzed, tests were carried out with various kinds of materials under various conditions in close cooperation between Hellweg International, the other contractors involved in the project and the Australian army.

A so-called 'soft solution' was eventually adopted. It is based on multiple layers of Twaron fabrics incorporated into a system, which can be quickly fitted as well as replaced. Twaron fabric was the best solution as it offered the lowest incremental weight factor which is easy to install and any damaged liners could be quickly replaced in the field.