Ultra-long endurance UAV flies using variable-buoyancy propulsion
Updated: Apr 25, 2019
A group of UK researchers led by Andrew Rae, professor of Engineering at the University of the Highlands and Islands Perth College UHI Campus (Perth, U.K.), has successfully flown the first ever large-scale aircraft powered by variable-buoyancy propulsion. The Phoenix unmanned aerial vehicle (UAV) is designed to repeatedly transition from being lighter than air to being heavier than air, generating thrust to propel the craft forward.
“This system allows the Phoenix to be completely self-sufficient,” says Rae. “The energy needed to power its pumps and valves is provided by a battery which is charged by lightweight flexible solar cells on its wings and tail.”
The prototype aeroplane has a fuselage containing helium that allows it to ascend like a hot air balloon. An air bag then brings in outside air and compresses it, making the vehicle heavier and triggering its descent. The resulting rising-and-diving motion (aided by the release of the compressed air) propels the aircraft forward as it glides on carbon fiber wings.
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