We have developed four winged, bird-like robots called ornithopters that can take off and fly with rapid oscillations, hummingbirds and insects. We did this by performing reverse aerodynamic and biomechanical engineering of these creatures.
Our ornithopters can outperform and outperform existing drone configurations with static wings or propellers.
What are ornithopts?
Ornithopters fly according to bird design. Existing drone configurations depend on propellers and static wings. Ornithopters fold their wings to bring them forward. The complex relationship between aerodynamics and wing movement allows birds and insects to fly in ways that are not possible with conventional drones.
Why do we want ornithopters?
Ornithopters fly differently than conventional drones. They can ski, clog and do aerobatic flying. In different situations, they can either save energy by flying like a regular airplane, or choose to fly. They can ascend and slowly descend in tight spaces, but can ascend quickly to freeze like a bird.
Current multi-rotor drones fly very nicely, but they use even more energy when moving forward than when flying, so they can’t travel far. Fixed-wing drones can move efficiently at high speeds, but tilting is usually not possible without damaging the entire structure. There are hybrid concepts, mostly with wings and rotors. Hybrid aircraft, given the extra weight, run and run poorly, due to the extra weight and towing from more parts.
Winged wings are an original solution in nature when you need to fly fast and slow, as well as land and take off from anywhere. For a bird or insect, each part of the system is used to fly and cruise without carrying unnecessary pistons or extra wings.
Existing fixed and swivel wing drones are so well understood that designs are now almost as effective as they can be. Adding something new costs other performance aspects as well.
In principle, ornithopters can perform more complex tasks than conventional aircraft, such as flying long distances, sometimes flying and maneuvering in tight spaces. Ornithopters are less noisy and safer to use around humans because they have a large wing area and slow beating wings.
How to make a working ornithopter?
An ornithopter is a very complex system. Until now, the wings of wings flew slowly and could not reach the speed and power required for vertical acrobatic driving or continuous flying.
Several ornithopters for sale are designed for forward flight. They climb slowly like unattended planes and cannot take off or take off vertically.
Our designs differ in several ways.
The difference is that our ornithopters use the clan and run effect. The two pairs of wings fold so as to stick together, as if the hands were whipping. This provides enough extra strength to increase their body weight during lifting.
We improved efficiency by aligning the wing / hull hinge to store and recover moving wing energy when the wings change like a spring. We also learned that most of the energy loss was due to the gears moving by tilting the wing. We solved this by using small bearings and rearranging the transmission shafts so that the gears were positioned correctly.
A large tail consisting of a steering wheel and a hoist creates a high turning force. This allows for aggressive acrobatic maneuvers and a quick transition from horizontal to vertical flight.
The system was designed to be able to lift the nose up, quickly increasing its angle of attack to a point where the wing does not cause a lift, a phenomenon called a “dynamic kiosk”.
The dynamic kiosk creates a lot of towing, turning the wing into a parachute to slow down the aircraft. This would be undesirable in many drones, but the ability to enter this state and recover quickly increases maneuverability. This is useful when working in a polluted environment or landing on a perch.
Catch up with evolution
One of the main conclusions of our work was that a practical ornithopter can achieve similar efficiencies as a propeller-driven aircraft. By releasing the extra power, the ornithopter was able to behave several times.
This has, in fact, shown that aircraft optimization is essential to make these new aircraft designs viable. We are now working to use wing designs copied from nature. We expect the same big improvements.
In some respects, such a large increase in efficiency as a result of these changes to the new systems should come as no surprise. Winged organisms have been optimized over hundreds of millions of years due to evolution. We humans have been in it for less than 200 years.
Javaan Chahl, Joint Department of Sensor Systems, DST Group, South Australia.
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