A flapping-wing drone capable of swift-like aerobatics

A team from Temasek Laboratories at NUS and their collaborators have developed a flapping-wing aircraft that flies agilely like a swift. This innovation could be a safer, quieter and more manoeuvrable alternative to drones in future.

A team of researchers has developed a 26-gram flying machine that flaps, swoops, and dives just like a bird. Known as an ‘ornithopter’, the invention can hover, dart, turn rapidly, and pull up from a dive with ease by adjusting its tail. As such, this flying vehicle blends characteristics from paragliders, aeroplanes and helicopters all in one.

With their innovation, the team from NUS Temasek Laboratories, in collaboration with researchers from the Nanyang Technological University, National Chiao Tung University, Australia’s Defence Science and Technology Group, the Qingdao University of Technology, and the University of South Australia, have shown for the first time an ornithopter which can change direction swiftly at high speeds.

These rapid decelerations and turns would allow the ornithopter easily avoid obstacles and fly in cluttered and unstructured spaces. Aerobatic manoeuvres such as these had previously not been demonstrated in flapping wing craft due to limited thrust and control.

As ornithopters fly without propellers, they are considered to be a safer and quieter alternative when compared to conventional quadcopter drones. Hence, the team hopes that their research will lead to low-risk and less intrusive drones in the future.

This work was published in the prestigious journal Science Robotics on 22 July 2020.

How to create a robotic bird

The team started by creating a flapping wing flying machine capable of high thrust generation at reduced energetic cost. Their effort was focused on the flapping mechanism design to reduce the power loss associated with friction and the recovery of wing’s kinetic energy. They managed to optimise the ornithopter to perform aggressive flight manoeuvres with high efficiency and high thrust.

The X-wing ornithopter is 20cm long. It uses tail elevation and high thrust, to hover, fly fast forward, turn aerobatically, and dive with smooth transitions. It is able to change direction within a 32mm turning arc and decelerates at 31.4m/s2. This ornithopter can also recover to glide stability without tumbling after a 90-degree body flip.

The ornithopter also consumes 40 per cent less maximum electrical power for the same thrust generation than the direct drive of a propeller. The triple roles of flapping wings for propulsion, lift and drag enable the performance of aggressive flight by simply controlling the tail.

Next steps

The team is looking into more applications for this type of flying machine, especially for indoor usage. The researchers believe such agile and safe flying machines could be deployed to pollinate indoor vertical farms in the future. Unlike traditional quadcopters, the flapping propulsion can operate in dense vegetation without cutting or shredding the plants. Traditional drones, with rotary propulsion run the risk acting almost like a lawn mower for grass cutting.