The Da Vinci Drone

For more than 500 years, Leonardo da Vinci’s “aerial screw”—an early proto-helicopter design—has graced a page of the Renaissance mastermind’s famous journals; but now, University of Maryland aerospace engineering students have given the idea a modern spin.

At a Vertical Flight Society conference last month, they unveiled their working prototype, “Crimson Spin,” which flies through the combined lift of four, whirring spiral-shaped blades.

The craft was the culmination of more than two years’ work stemming from the University of Maryland’s winning graduate entry—Elico—in the society’s Leonardo-themed student design competition in 2020.

“When we first tackled this challenge as part of the Vertical Flight Society’s original call for proposals, we recognized that there was a serious possibility that it just wasn’t even possible to fly with an air screw,” said Elico team member, Ilya Semenov M.S. ’20, who helped conduct experiments to measure lift and rotor structure modeling. “The whole point of the competition was to evaluate whether this old, ancient concept could even work at all.”

The team’s winning design did, in fact, look functional on paper and in computer simulations, but could it fly?

“We saw some really interesting behaviors in the lift mechanisms of the air screw in our computational fluid dynamics simulations and models where we found this interesting edge vortex that would form,” explained Semenov. “But with such a novel design, we couldn’t be 100% sure that the phenomenon was true, so creating a working model would help us validate if that was in fact happening.”

Encouraged by Distinguished University Professor Inderjit Chopra, one of the faculty members who helped supervise the team, Austin Prete M.S. ’22 spent the next year and a half taking Elico from a theoretical working model to a functional prototype. He was responsible for not only the prototype development and flight testing, but building and repairing all of the aerial screws.

“That first successful flight was an incredible moment,” said Prete. “It took three months, just trying to get it to fly correctly. I had to just step back and take a moment.”

While the research and findings are too preliminary to envision potential applications at this point, the functional prototype is a starting point.

“Just the way the air screw worked was surprising,” said James Sutherland, Ph.D. candidate and team captain of the 2020 design team. “It’s possible that the aerial screw might be less noisy, or create less downwash [a downward blast of air from rotorcraft] than a regular rotor with the same amount of thrust.”

Prete said that one interesting finding was that the screws can create the same amount of lift but with less rotations compared to a traditional rotor, which may contribute to the reduced downwash—a significant issue when flying traditional rotorcraft in areas where debris can be kicked up.

Looking ahead, Prete and his Elico team members—who are all graduating after this semester—hope work continues on the aerial screw.

“I’d like to see work continue to improve the performance and climbing capabilities as well as the vehicle’s ability to hover,” said Prete.

UMD intends to continue pursuing a more detailed study on this topic.

“We are exploring the possibility of sponsored work with some funding agency,” said Chopra. “The objective is to advance the aeromechanics design tools focused on the da Vinci Aerial Screw for a vertical lift system.”

Read the original news release.