When a Royal Marine was shot in Afghanistan in January last year during a vicious battle in an old desert fort, his colleagues could not find him in the confusion. As they pulled back to regroup, concern grew that Taliban insurgents had captured him.
Within minutes, the marines had launched a Lockheed Martin Desert Hawk mini-unmanned aerial vehicle (UAV) to find out what was happening behind enemy lines. Pictures downloaded in real time from the Desert Hawk into a briefcase-sized control unit showed the body in the centre of the fort.
Unsure whether their colleague was dead or wounded, the marines organised a daring rescue mission in which four men strapped themselves on to the outside of two Apache attack helicopters. Unfortunately, by the time they reached their stricken friend, he was dead, but the rescuers were able to retrieve his body.
The incident illustrates the potential advantages of mini-UAVs — or micro air vehicles (MAVs) — that can be carried in a soldier's backpack and used to deliver images to frontline troops.
As well as their operational appeal, MAVs cost a fraction of their larger cousins such as the Predator, Reaper and Global Hawk — tens of thousands rather than millions of pounds for a single system. General Atomics' airliner-sized Reaper UAV can cost more than £5m, excluding the tens of millions of pounds for the supporting communications infrastructure.
The diminutive class of UAV began to earn recognition during the past seven years of conflict in Iraq and Afghanistan. The first front-line users were highly secret special forces operatives who used their 'black' or covert equipment budgets to sidestep conservative procurement bureaucracies and buy large numbers of MAVs for use in the war on terror.
The main reason behind these purchases was the need to over-fly remote Afghan mountain ridges to try to spot small groups of Taliban lying in wait to ambush coalition forces. Britain's elite Special Air Service is known to have tested the Buster mini-UAV, and the regiment's US counterpart was the first big customer for these revolutionary systems. Now most US and British bases in Iraq and Afghanistan have their own flight of mini-UAVs to patrol the perimeter around the clock, looking for hostile forces.
The defining feature of MAVs is that they can be carried and deployed by a single soldier. This means the air vehicle, radio downlink and control unit can all be packed into a single rucksack, then taken into a combat zone.
Beyond this, the market is filled with a diverse array of products. Many are little more than glorified remote-control model aircraft that can be thrown into the air by a soldier. A hand-held remote or joystick control unit is used to fly the craft. These cheap and cheerful products, however, suffer from high wastage rates from accidents and hard landings.
Lockheed Martin's Desert Hawk is now an established reconnaissance tool
Top-end products have a fan jet or helicopter-style propulsion system that allow vertical take-off and landing. Many feature automated flight control systems that only require the operator to programme in co-ordinates of way points, and the aircraft flies itself for the duration of the mission.
Meanwhile, the operator concentrates on monitoring imagery from the MAV's on-board cameras. This allows more reliable operation and can be weighed against the high loss rates for cheaper systems.
The relatively low cost of mini-UAVs means the price of entry into the market for smaller companies is manageable, so many of them are produced by names not usually associated with defence. It also means rapid technical advances can be made for the investment of a few hundred thousand pounds.
Typical of the speed of innovation in the sector was the award in August this year to the Californian company AeroVironment, a leading player in the global mini-UAV market, of $4.6m (£2.5m) in funding from the Pentagon's think tank, the Defence Advanced Research Projects Agency, to develop its small unmanned aircraft system (UAS) capable of performing 'hover/perch and stare' missions.
The Stealthy, Persistent, Perch and Stare (SP2S) UAS is based on AeroVironment's Wasp, a 0.45kg, 74cm-wingspan, battery-powered craft being procured and deployed by the US Air Force and the US Marine Corps.
The aim is to develop the technology to enable an entirely new generation of micro vehicles capable of flying to difficult targets, maintaining a 'perch' position, conducting sustained perch-and-stare surveillance missions, then returning to its base.
'A UAS that performs hover/perch and stare missions is viewed as an important capability for our armed forces,' said John Grabowsky, AeroVironment's general manager of unmanned aircraft systems.
Many armed forces have visions of using mini-UAVs as part of wider robotic warfare, in which swarms of air- and land-based robots would dominate battlefields of the future.
In August, the UK Ministry of Defence's Grand Challenge technology competition (The Engineer, 11 February) saw 11 teams, drawn from industry and academia, put innovative robot warfare systems to the test at the British Army's Copehill Down urban warfare training complex on Salisbury Plain, Wiltshire.
Essex University's Prof Owen Holland, a consultant for one of the 11 competitors, Team Swarm, explained the benefits of using a swarm approach: 'Swarming has many proven advantages. Most importantly, it can survive unexpected events. If one vehicle is suddenly lost, the swarm reconfigures itself to complete the task.'
Team Swarm used eight quadrotors called Owls. Their operator used three-dimensional planning software to swiftly plan and rehearse routes for the Owls over Copehill Down village. The craft then flew those routes, taking hundreds of high-resolution images. On their return, these images were processed by a cluster of 10 powerful multi-processor PCs, which analysed each image using the University of Surrey's threat recognition software. Within minutes, the operator had produced a map of Copehill Down showing the location and type of all recognised threats.
The winner of the Grand Challenge was Team Stellar, which entered Saturn — an integrated system with one high-flying and one mini-UAV and an unmanned ground vehicle, with a control station fusing data from visual, thermal and radar sensors. It was awarded the highest score by a panel of judges after its vehicles successfully identified a range of threats planted in the village, including actors dressed as militia.
Mini-UAVs have come on in leaps and bounds in the past seven years, but they have limitations and are not a panacea for military intelligence-gathering requirements. It is, however, clear that they are here to stay.
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