Jul 23 2020
A swift is one of the world’s fastest birds. An international group of aerospace engineers is developing a drone prototype that imitates the aerobatic maneuvers of this bird in the new example of biologically-inspired flight.
Dr Yao-Wei Chin with the flapping wing drone prototype. Image Credit: University of South Australia.
A group of researchers from Taiwan, China, Singapore, and South Australia has developed a 26-g ornithopter (that is, a flapping-wing aircraft) that can glide, dart, hover, dive, and brake similar to a swift, rendering it safer, quieter, and more versatile when compared to present-day quadcopter drones.
The flapping wing drone, whose weight corresponds to two tablespoons of flour, has been improved to fly in cluttered surroundings close to humans, with the potential to hover at extremely low power, glide, and brake rapidly from quick speeds, preventing collisions—all the things that could not be done by quadcopters.
The research group includes Professor Javaan Chahl, an aerospace engineer from the University of South Australia (UniSA) who developed a flapping wing drone, the size of which is similar to the swift bird, or a large moth, that can carry out certain aggressive bird flight maneuvers.
According to Professor Chahl, mimicking the design of birds, such as swifts, is just one of the plans to enhance the flight performance of the flapping wing drones.
There are existing ornithopters but, until now, they were too inefficient and slow to be agile. We have overcome these issues with our flapping wing prototype, achieving the same thrust generated by a propeller.
Javaan Chahl, Professor, Aerospace Engineer, University of South Australia
Chahl continued, “Flapping wings can lift like an aeroplane wing, while making thrust like a propeller and braking like a parachute. We have put this together to replicate the aggressive flight patterns of birds by simple tail control.”
According to Dr Yao-Wei Chin, a research scientist from the National University of Singapore, who headed the study published recently in the Science Robotics journal, the biologically-inspired drones could be effectively employed in a variety of surroundings.
While the surveillance applications are quite evident, innovative applications comprise pollination of indoor vertical farms without destroying thick vegetation, in contrast to the rotary-propelled quadcopters whose blades are likely to shred crops.
Since the ornithopter remains stable even in strong winds, it could also be used for chasing birds away from airports. This would prevent the birds from being sucked into the jet engines.
The optimized ornithopter acts as a kind of scarecrow, greatly saving on labor costs for pest control companies and airport operators.
Dr Yao-Wei Chin, Research Scientist, National University of Singapore
The scientists claimed that no commercialized ornithopters are presently used for surveillance, but this trend could change thanks to the latest discovery.
Enhancing the design of ornithopters would allow them to create a sufficient amount of thrust to hover as well as carry a camera and associated electronics. Such optimized designs could make it viable to use the flapping wing drone for gathering information, surveying wildlife and forests, and monitoring crowd and traffic.
The ornithopter has slow-beating and lightweight wings, which means it poses less harm to the public when compared to other quadcopter drones in the event of a crash. If enough thrust and power banks are given to the ornithopter, it could be adapted to carry different payloads based on what is needed.
But one area that needs additional research is the way birds will respond to a mechanical flying object that resembles them in shape and size. While drones can easily frighten tiny, domesticated birds, ornithopters have been attacked by huge flocks of birds and relatively bigger birds.
According to Dr Chin, while the bio-inspired breakthrough is certainly impressive, more studies are required to simulate biological flight.
Although ornithopters are the closest to biological flight with their flapping wing propulsion, birds and insects have multiple sets of muscles which enable them to fly incredibly fast, fold their wings, twist, open feather slots and save energy.
Dr Yao-Wei Chin, Research Scientist, National University of Singapore
“Their wing agility allows them to turn their body in mid-air while still flapping at different speeds and angles. Common swifts can cruise at a maximum speed of 31 meters a second, equivalent to 112 kilometers per hour or 90 miles per hour. At most, I would say we are replicating 10 per cent of biological flight,” Chin concluded.
Journal Reference:
Chin, Y.-W., et al. (2020) Efficient flapping wing drone arrests high-speed flight using post-stall soaring. Science Robotics. doi.org/10.1126/scirobotics.aba2386.