An unmanned seaplane being developed to perform persistent ocean surveillance has demonstrated autonomous take-offs and landings in tests off the coast of California.

Designed by the University of Michigan, the Flying Fish UAV is being developed to meet the requirement for an energy-efficient environmental monitoring buoy that can remain in position in the deep ocean for long periods of time without being moored, says Guy Meadows, director of the U-M Marine Hydrodynamics Laboratories.

Developed under the US Defense Advanced Research Projects Agency's persistent ocean surveillance programme, the electric-powered UAV has a 2.1m (7ft) wingspan and is "about the size of a large pelican", he says.

While a small boat trying to maintain position would waste energy climbing waves, the UAV mimics seabirds, which drift then reposition themselves by taking off, flying low over the water and landing. "We have made a robotic pelican," Meadows says.

Onboard GPS is used to define a watch circle. The UAV is allowed to drift from the centre until it reaches the edge of the circle, where the autonomous take-off triggers. The UAV flies to the other side of the circle, lands and begins drifting until the sequence repeats.

Sea trials of the battery-powered UAV off Monterey involved 22 autonomous take-offs and landings. U-M now plans to fit solar cells and sensors to detect and avoid waves. "We need to maintain a balanced energy budget. The next step is to put solar cells on to the wing and see how often and how far it can fly," he says.

Source: Flight International