Persistent surveillance is becoming a pressing requirement for US forces, spawning a number of programmes aimed at demonstrating unmanned air vehicles with endurance capabilities ranging from weeks to years.

The latest of these is the US Defense Advanced Research Projects Agency’s (DARPA) VULTURE programme to demonstrate the ability to keep a heavier-than-air UAV on station for more than five years.

VULTURE – which stands for Very-high altitude, Ultra-endurance, Loitering Theatre Unmanned Reconnaissance Element – is a complement to DARPA’s ISIS (Integrated Sensor Is Structure) programme to demonstrate technology for an unmanned airship capable of remaining on station in the stratosphere for a year or more.

DARPA has invited proposals for the VULTURE programme and plans an industry day on 7 June. The agency is looking for the capability to “deliver and maintain a 1,000lb, 5kW airborne payload for an uninterrupted period exceeding five years with a 99%+ on-station reliability”.

“VULTURE, in effect, will be a retaskable, persistent satellite capability in an aircraft package,” says DARPA in its fiscal year 2008 budget submission, which indicates the UAV will be solar powered, like the ISIS airship.

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