For years, unmanned aerial vehicles (UAVs) had been the mainstay of skies above battlefields and found snooping behind enemy lines. But with GPS technology becoming more readily available, the clever equipment is finding its way onto UK farms.

Flying Eye UK is the latest company to offer reconnaissance-style crop videoing and remote sensing. The company, based in Chessington, Surrey, is looking to develop its fleet of unmanned helicopters to be used to monitor field and crop condition.

It has both normal-type twin rotor machines and more stable-looking multi-rotor helicopters. Screwed precariously to the undercarriage is a Canon 550D camera, so both still pictures and video can be recorded and downloaded or viewed in real time on a base station monitor.

All of the helicopters can be controlled either remotely, using a handset similar to any other remote-control machine, or via GPS.

The machines work like a sat-nav by using up to 12 satellites to get an accurate position. It means you can plan routes across fields and get pictures that can be stitched together to provide a complete view of the farm or field.

The helicopters are weather sensitive – gusts of more than 20mph cause sea-sickness-inducing footage and make flying a risky business – and batteries only last nine minutes (although the company says this is adequate). The machines can cost as much as £20,000 and a day of video surveillance about £1,000.

It’s not the first UAV to be used for farmland monitoring, though. The Ursula unmanned aircraft is part of an Aberystwyth-based research programme. The aircraft can complete remote sensing of mainly arable crops and will record about 250ha during a 30-minute flight. It is hoped that Ursula will be able to provide field management information on nutrition, seed rate and stress detection.

Elsewhere, Trimble partner Korec’s Swinglet is a lightweight UAV with built-in 12 megapixel digital camera. The electrically powered plane can operate up to 20km away and in winds of up to 15mph. Flight paths are pre-programmable and the e-mo-tion computer system can then stitch together photos to provide a complete view of the fields. Berkshire company VTOL technologies is also developing a UAV capable of both crop monitoring and crime control.