Drone follows Leonardo da Vinci's 530-year-old design

A team of engineers at the University of Maryland built a 4-rotor drone with a unique spiral shape and successfully tested it.

In the late 1480s, genius Leonardo da Vinci sketched a unique design for a helicopter powered by "aerial screws" - propellers that twist like the grooves of a screw. However, at that time he was unable to build a machine that actually worked.

Leonardo da Vinci's airplane design in the 1480s.

In 2019, a group of engineers at the University of Maryland, USA, researched and tested the above idea in a design competition. Then, for the past year and a half, team member Austin Prete has spent time developing and crafting the Crimson Spin. This is a drone model with 4 spiral propellers like da Vinci's design, which has been tested for short distances.

"I was absolutely amazed that it worked," said Prete, a graduate student in the University of Maryland's aerospace engineering department. Initially, he and the other team members doubted the feasibility. However, they became increasingly excited about da Vinci's designs as several computer simulations and 3D printed prototypes demonstrated their potential. Prete presented the research findings at the Transformative Vertical Flight 2022 conference in San Jose, California, January 25-27.

Drone Crimson Spin test flight. (Video: Cnet/Austin Prete/University of Maryland)

Prete has only built a small drone, but the technology can be applied to an aircraft large enough to carry people. "I believe it can scale up quite a bit," he said.

When crafting the Crimson Spin, Prete benefited from materials da Vinci did not have. Advanced Renaissance building materials, such as wood and leather, were too thick for airplanes. Da Vinci also does not have a compact power supply system.

Meanwhile, Prete can use aluminum, plastic, electric motor, battery and computer control system to help realize the design of the screw in the air. In addition, he uses computer-aided design and fluid dynamics computing software to design prototypes and simulate computer aerodynamics.

Today's 4-rotor drone technology also helps realize da Vinci's design. This type of drone moves thanks to subtle changes in propeller speed, causing the aircraft to tilt in one direction or another. Prete said it would be much more complicated to try to build a single-axis prototype like a traditional helicopter. However, twist-rotor drones also face many challenges, including the high weight of overhead screws and the risk of instability.

In addition, Prete discovered some strange aerodynamic factors that may have helped the Crimson Spin fly. Delta-wing aircraft - aircraft with large triangular wings like the supersonic Concorde - create a swirl of air that passes over the front edge of the wing. This vortex creates an area of ​​low pressure that can increase lift. Simulations show a similar airflow forming along the out-of-plane edge of the overhead screw, swirling along the entire structure and creating an upward thrust.

One of the effects of this aerodynamic factor is that the overhead screw produces less downward airflow than traditional propellers. That means less dust and other matter is blown up below. In addition, this unique design can also help reduce noise.