Land - DEFENCE MANAGEMENT JOURNAL, Issue 56

PROFILE- Active blast protection systems

Not long after the IED threat developed in Iraq, Advanced Blast and Ballistic Systems Ltd. started to investigate the mechanism of the blast event itself, and the principles required of an active system designed to counteract the effects of under-belly mine blasts. High-speed video of a blast test on a light armoured vehicle showed that there is about a 10 millisecond time window before the whole vehicle begins to move globally, during which time a counter-action to a mine blast can be initiated to mitigate the resulting global acceleration.

It was also concluded that generating a downwards-acting force on the top of the vehicle could be effective in reducing the global acceleration threat to the crew. Hence initially, in 2008, work was focused on mitigating this threat, and rising platform tests in 2009, followed by full-scale vehicle test work in 2010 demonstrated the technical feasibility of reducing global acceleration levels, and potentially eliminating it completely at specific mine blast levels.

The Vehicle Global Acceleration Mitigation (VGAM) system and Vehicle Armoured Floor Stabilisation (VAFS) development
Following the full-scale vehicle tests, it was realised that if the downwards-acting force holding the vehicle down was transmitted directly to the floor/belly plate structure through a structural column passing through the vehicle cabin, the floor deformation would be reduced as well as the global acceleration. This concept was termed Vehicle Armoured Floor Stabilisation (VAFS).

The basic principle of both the VAFS and the VGAM systems is the use of explosive force against explosive force, and this is many times more weight-effective than using more metal to reduce deformation of the belly plate and vehicle floor structure. This gives the potential for weight savings in the belly plate, whilst still achieving the same or higher under-belly blast specification for the vehicle.
In principle, the application of the systems can be used to either increase the mine blast capability of a vehicle for the same weight, or provide the same mine blast capability at reduced weight.

Additionally, applying the combined VAFS/VGAM system could potentially lead to:
•A significant reduction in ground clearance to lower the vehicle's centre of gravity and improve its stability without reducing its mine blast resistance level;
•Reduced clearance between the vehicle belly plate and the internal floor, allowing a lower floor and an increase in internal volume for the crew and storage space;
•The possibility of eliminating the standard blast mitigating seats, or reducing the stroke requirement necessary for their function, thus increasing internal volume available.

Other potential active systems
Having identified the technical feasibility of effective explosively-driven active intervention systems to counteract the effects of mine blasts under vehicles, other mechanisms involving the belly plate/floor structure have been defined. These are also being evaluated and will be developed into systems working in combination with the VAFS and VGAM elements described previously.

Applicability and current status of ABBS active blast protection systems
The systems are applicable to any vehicle requiring significant under-belly mine blast protection, including light civilian/VIP cars and SUVs. The VGAM system makes it possible for the first time to mine protect such vehicles to a significant level. Previously, even if the belly plate structure was sufficient to prevent penetration, the global acceleration would likely kill or severely injure the occupants. With the global acceleration controllable, and floor deformation also restricted, surviving under-belly SUV mine blast is now possible. Clearly, above the SUV-type, every type of armoured vehicle from LAV to MBT can benefit from application of the ABBS active blast protection systems.

ABBS is currently working with the UK MoD, armoured vehicle OEMs and other design teams to define and develop the active blast protection systems described here for specific vehicle applications, and welcomes contacts from any manufacturer or user interested in understanding what can be achieved.

Roger Sloman-Managing Director
Advanced Blast & Ballistic Systems Ltd.
Derbyshire DE6 3BH
Tel: +44 (0)1335 360641
Mobile: +44 (0)7989 381057
roger.sloman@advanced-blast.com
www.advanced-blast.com