When an improvised explosive device detonates under a military vehicle, it鈥檚 often not the blast that kills the people inside 鈥� it鈥檚 the extreme acceleration that snaps spines and severs arteries. But a new vehicle design that fits rocket motors to the top to exert an immediate and overwhelming counterforce could save the people inside.
The idea isn鈥檛 as mad as it may seem. The upward force of an IED blast can instantly catapult a vehicle many metres into the air. Although vehicle floors are strengthened to prevent IED hot blast gas and searing debris from directly hitting occupants, what often kills people are the internal injuries this jarring take-off acceleration causes to vital human organs.
But what if you exerted an equal and opposite downward force just at the moment of detonation?
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The possibility was always there 鈥� it鈥檚 just Newton鈥檚 laws applied creatively 鈥� but received military wisdom has always held that an IED blast happens too fast to allow for any countermeasures to engage in time.
But when Roger Sloman was analysing ultra-high speed video of a test detonation beneath an old Russian scout vehicle, he noticed something unexpected. Sloman, managing director of UK based countermeasures company , realised that after the blast, the vehicle remained in place a full 10 milliseconds before it began to move upwards. That was a time window he could work with.
120 tons of counterforce
So Sloman set to work figuring out what he could build to counteract the acceleration effects of the blast.
The system he developed detects a blast with crush sensors in the vehicle鈥檚 armoured floor. To聽counteract that blast, he worked with Daniel Jubb at Falcon Project, a solid rocket maker based in Westcott, Buckinghamshire, to develop and patent a wholly new kind of solid rocket motor. This so called linear rocket motor can聽react within 3 milliseconds.
Each LRM comprises a 1-metre-long square steel tube packed with 50 nozzles of electrically-ignited solid rocket fuel.
In tests in July, observed by the UK Ministry of Defence, an IED blew a Snatch Land Rover without the technology more than five metres into the air. But when a similar vehicle was fitted with two LRMs the vehicle stayed on the ground. 鈥淚t just bounced a bit at the back,鈥� says Sloman.
鈥淭he peak thrust from all those rocket nozzles is insane,鈥� Jubb says 鈥� just聽two LRMs in the test made the vehicle momentarily weigh around 120 tons.
The research was presented this week at a conference on in London.
Although IED incidents worldwide are declining, they in Afghanistan 鈥� so US forces may see a need for the LRM. 鈥淭his technology looks like it is going to be exceptionally useful,鈥� says Gregory Chambers, a former US Marine Corps armour specialist.
The LRMS could find other applications, too: downward facing rockets fitted on helicopter skids could be used to cushion crash landings, Sloman says, which could certainly be useful for some of the emerging 鈥渇lying cars鈥� being backed by Google and Uber.
