A protected personnel compartment and a sacrificial blast wedge could improve the safety of occupants of future light armoured patrol vehicles.
Researchers from the Georgia Tech Research Institute (GTRI) designed and tested such a concept, dubbed ULTRA II, for the US Office of Naval Research (ONR). A blast test conducted with the ULTRA II full-sized crew compartment at the US Aberdeen Test Center showed that the new concept could protect the vehicle crew from improvised explosions.
‘Instead of uparmouring a standard vehicle or modifying an existing drive train, we built a bubble of force protection first and then addressed vehicle mobility,’ said Vince Camp, a GTRI senior research engineer.
The ULTRA II crew compartment is designed to house six persons: a driver and commander facing forward and two pairs of crew members behind them, each pair facing opposite sides of the vehicle.
By putting their backs towards the centre of the crew compartment, the concept moves the crew away from the outside walls to reduce the likelihood of injury from side blasts, provides better visibility for the crew to monitor their surroundings and allows blast-resistant seats to be frame mounted.
The crew compartment envisioned by the GTRI uses a space frame constructed of tubular steel, similar to civilian off-road racing vehicles. An armoured steel skin provides added structure and moderate ballistic and blast protection. Additional armour is bolted onto the frame in a modular way, allowing varying levels of protection that could be modified in the field and changed as new armour concepts are developed.
An integral part of the protection is provided by the sacrificial blast wedge bolted onto the bottom of the vehicle. Constructed of welded steel armour, the wedge both deflects energy away from the vehicle and absorbs energy from a blast, performing a function similar to crumple zones in cars.
A test of the design at the Aerospace, Transportation and Advanced Systems Laboratory of the GTRI with instrumented dummies simulating a crew showed that the wedge deflected or absorbed nearly 70 per cent of the energy from an explosion beneath it. Damage from the blast was primarily confined to the sacrificial blast wedge and there was no structural damage and no blast penetration to the crew compartment.
‘Data from the instrumented dummies shows that, had this test been conducted with real warfighters in a real vehicle, we wouldn’t have seen any spinal injuries, head trauma, neck trauma or leg injuries,’ said Kevin Massey, a GTRI senior research engineer who was part of the project team.
As the wedge is removable, it can be replaced if damaged. Making the blast wedge removable also allows for an overall reduction of the vehicle’s height for shipping – an important issue for rapid deployment.
In addition to crew protection, the researchers also designed a door that would provide a large side opening, similar to that of existing civilian minivans. Such a door system would provide improved ingress/egress for the crew and could remain open when the vehicle is moving.
The GTRI has presented the data from its test to the ONR and hopes to pursue additional refinements to the blast wedge and overall vehicle concept. Among the goals would be to improve energy absorption from the wedge and to evaluate whether the crew compartment should separate from the drive train in certain types of blasts.
GTRI researchers Kevin Massey, Vince Camp and Burt Jennings (left to right) with the ULTRA II as it was set up for evaluation at the Aberdeen Test Center in Maryland