- Leonardo da Vinci's 1480 aerial screw could inspire a quieter drone rotor design
- Johns Hopkins team found the aerial screw needs less power for equal lift
- Simulations showed the aerial screw rotates slower, reducing power use
A flying machine resembling a helicopter, designed by Leonardo da Vinci, could be used to develop quieter and stealthier modern drones, according to a new study published in the journal Bulletin of the American Physical Society. Famous for his paintings such as the Mona Lisa and The Last Supper, Da Vinci was also an engineer and architect who conceptualised flying machines centuries before any of these machines became a reality for humans.
The prototype helicopter called Leonardo's aerial screw was conceived in 1480 and is regarded as the earliest known designs for a lift-generating rotor. Rajat Mittal at Johns Hopkins University in Maryland and his colleagues found that the "aerial screw" may require less power to generate the same amount of lift as a conventional drone rotor.
"We were surprised," said Mr Mittal, adding: "We went in thinking that because the shape of this spiral screw is just completely, in some sense, ad hoc, it was intuitive that the aerodynamic performance would be so bad that we would not be able to get any improvements over conventional blades."
The researchers built a simulation of the device and put it in a virtual wind tunnel to examine how it would perform while hovering in place. They found the aerial screw could generate the same amount of lift while rotating more slowly, meaning it would consume less power.
“The da Vinci propeller produced much less noise for the same given amount of lift being generated," said Suryansh Prakhar, a doctoral candidate in mechanical engineering who worked on the project.
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The team is now planning to conduct more simulations to model the propellers' noise levels when the drones are larger and operating at higher speeds.
“We would expect similar results in noise reduction; however, the aerodynamic efficiency of da Vinci's propeller will be lower when compared to a traditional propeller since not all parts of the spiral screw shape can be optimized to produce a similar amount of lift force
Modern drones produce a high-pitched buzz sound as the propellers cut through the air. With their use for delivery, emergency response, photography and warfare rapidly increasing, these remotely operated vehicles continue to become bulky and noisy. However, if the study is anything to go by, the drone-making process could be revolutionised.
