A solar-powered aircraft that can stay in the air for prolonged periods of time by "inhaling" air to move has been created by scientists in the UK.
The Phoenix unmanned aerial vehicle (UAV) is able to propel itself forward autonomously by repeatedly switching from being lighter than air to being heavier than air, to generate thrust.
"The vehicle's fuselage contains helium to allow it to ascend and also contains an air bag which inhales and compresses air to enable the craft to descend," said Andrew Rae, professor of engineering at the University of the Highlands and Islands, which is among five universities working on Phoenix.
"This motion propels the aeroplane forwards and is assisted by the release of the compressed air through a rear vent."
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The prototype 15-metre long and 120kg aircraft was successfully tested for the first time in an indoor facility in Portsmouth in March, over a distance of 120 metres, multiple times.
Experts working on the project for the last three years believe it could eventually go much further for low-level satellites, GPRS systems and surveillance.
"Under autonomous mode, it can be left to its own devices," said Gary Owen, materials consultant at Banks Sails, who worked on fuselage materials and manufacturing.
"The ultimate aim is to have it at 20,000 metres, though it's not at that stage at the moment."
Solar panels on the wings enable the Phoenix to be completely self-sufficient, researchers say. At very high altitudes, the system could allow it to fly for months.
Experts from the University of Bristol, University of Newcastle, University of Sheffield and University of Southampton also collaborated on the project with companies across the country.
They claim that vehicles based on this technology, known as "variable-buoyancy propulsion", could provide a cheaper option for telecommunication activities.
"Current equivalent aeroplanes are very complex and very expensive," Professor Rae continued.
"By contrast, Phoenix is almost expendable and so provides a user with previously unavailable options."
