Flying drone inspired by swimming jellyfish
Scientists have built what they say is the first flying machine that hovers in a stable manner by flapping its wings.
Previous designs for so-called flapping wing aircraft have mimicked the wing motions of insects, but the new design is based on the way jellyfish swim.
The prototype built by scientists at New York University is able to keep upright and recover from disturbances.
The authors say their machine shows the value of researching flying strategies not yet explored by evolution.
The work by Leif Ristroph and Stephen Childress from New York University (NYU) is published in the UK Royal Society journal Interface.
Most efforts to build stable flapping-wing aircraft - or ornithopters - have based their designs on the way insects fly.
But this approach leads to aircraft that are inherently unstable, tending to flip over if left to their own devices.
Stabilising these designs requires either active control systems, or the addition of sails and tails that act as aerodynamic dampers.
Using jellyfish as one inspiration, the researchers set out to achieve stable hovering using flapping wings alone.
They developed a 10cm prototype with four distinct wings that demonstrated an inherent tendency to remain upright during flight.
"In the future, small-scale flapping-wing aircraft may be used in applications ranging from surveillance and reconnaissance missions to traffic and air quality monitoring," the researchers write in Interface journal.
They added that the flying machine they had developed was a step towards such a device.
"Depending on the application, active control over an intrinsically unstable design may be more desirable than passive stability," Ristroph and Childress added.
"In all cases, understanding the inherent flight dynamics is important for devising the control schemes needed for manoeuvring and for keeping upright and on-course in the face of unexpected disturbances."