09/29/2011 Neil Waghorn defenceiq.com
Improvised Explosive Devices (IEDs) are one of the biggest threats for vehicles in Afghanistan. According to figures obtained by the Washington Post from the Joint IED Defeat Organisation, the
number of IED attacks in Afghanistan reached 14,661 in 2010, with 2011’s figures set to be even higher. This threat has lead to many nations across the globe investing in IED protection. While
the sophistication of IEDs varies wildly – from artillery shells connected to a simple pressure plate to homemade explosives detonated by remote control – there is a limited number of ways for a
vehicle to survive an IED.
The optimum way for a vehicle to survive an IED blast is for there not to be a blast in the first place. The neutralisation of the IED threat can be achieved through a variety of methods. The
surveillance and targeting of critical nodes in the insurgent network is one method, potentially resulting in the network’s paralysis. Intelligence on IED locations produced by the local
population can also help mitigate the threats. Technology, such as signal jammers, can also help reduce the threat by preventing radio detonation of IEDs. However, assuming that the threat cannot
be completely eliminated, it is important to assess the options available for ensuring vehicle survivability, focusing on armour and hull design.
A cycle of upgrades
The immediate reaction to an IED threat is to increase the armour on a vehicle, making it more survivable. This, however, causes a cycle of upgrades. The enemy will simply increase the size of
the IED, requiring a need for yet increased armour. For the vehicle, however, this cycle may not be sustainable.
There is a limit to the amount of armour that you can put on a vehicle before it becomes impractical. At what point does a light vehicle start to resemble a tank? Heavy Mine Resistant Ambush
Protected (MRAP) vehicles can struggle off-road and be too heavy to go across some bridges in Afghanistan, with some MRAPs reportedly weighing in at up to 30 tons – depending on the model,
equipment and load. Armour has always been a trade off between protection and speed and manoeuvrability. The aim is to find an acceptable position somewhere in the middle that offers both
protection and speed.
Channelling the blast
Faced with the limitations of heavy armour, the focus is further shifting to ways to channel and deflect the force of the blast instead of attempting to just block it. One existing approach is the use of V-shaped hulls.
Originally developed in South Africa to combat the use of landmines in the bush of Southern Africa, the objective of this hull design is to deflect the force of the blast outwards and upwards, away from the inhabitants of the vehicle. V-shaped hulls are becoming increasingly common on new armoured vehicle designs such as the Ocelot - produced by Force Protection Europe - helping raise IED survivability.
A progression of this thinking has led to the development of a new technology: Structural Blast Chimneys. The concept behind this structural change is that the chimney will act as a pressure release valve, allowing the force of the blast to be released safely up through the centre of the vehicle. A potential issue with V-shaped hull vehicles is that they tend to have a high centre of gravity and the force of an IED blast can cause the vehicle to roll over. According to a June 2008 report by the US Marine Corps Center for Lessons Learned, of the 38 MRAP accidents between November 7th and June 8th 2008, only 4 did not involve a MRAP rolling over. This can cause harm to the occupants of the vehicle. A structural blast chimney would help counter this, with the force of the explosion coming out the chimney pushing downwards and keeping the vehicle on the road. According to an interview with Defencenews.com, the CEO of Hardwire George Tunis stated that “in the instant of a blast, a 15,000-pound vehicle will effectively weigh closer to 60,000 pounds” due to the thrust coming out the chimney.
DARPA testing
The American Defense Advanced Research Projects Agency (DARPA) is combining V-shaped hulls and Structural Blast Chimneys with other technologies in their ‘Topologically Ordered Armor’. DARPA has been testing its new armour at the Aberdeen Blast Test Center and results indicate ‘that a properly modified HMMWV may provide occupant survivability comparable to the M-ATV underbody at nearly half the weight’. The light weight, in comparison to MRAP and M-ATV, ensures that upgraded HMMWVs will still be able to conduct off road operations with ease, without having to worry whether infrastructure such as bridges can take the load. The issues of moving upgraded vehicles to and around theatre are unlikely to be much greater than that for existing HMMWVs.
Senator Patrick Leahy, of the Senate Appropriations Defense Subcommittee, is reported to have summed up the advantages of the structural blast chimney, when he commented that “It comes in at less weight, considerably less weight, more mobility, a third of the cost, and so forth, of the MRAP," With the technology still undergoing tests, the exact final cost of a newly structurally altered vehicle, or how much it would cost to upgrade existing vehicles, is still unclear, but, as Sen. Leahy suggests, it is likely to be less than a new MRAP.
Although the Structural Blast Chimney was originally designed for integration with HMMWVs, US Army Secretary John McHugh has reportedly expressed to Congress that, if the system works, there is the potential for examining its implementation on other platforms.
The DARPA tests highlight that there is an alternative to simply increasing the armour on vehicles. A change in mindset and the willingness to accept structural changes can potentially provide the safety of armour without the traditional weaknesses - it may finally be possible to have both protection and manoeuvrability.
If these structural changes become standard in vehicles it will be interesting to see how Taliban insurgents respond. The likelihood is that the cycle of upgrades will start again, with both sides attempting to overcome their opponent’s latest tactic. It may be that increased levels of armour will be a solution, but structural changes may mean that vehicles can maintain a certain level of manoeuvrability.
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