Leonardo Da Vinci’s Spiral Rotor Beats Modern Drones in Noise and Power Tests By David Freeman - June 26, 2025
Leonardo da Vinci’s aerial screw, one of the most iconic blueprints in the history of flight, has now been vindicated by modern science in a way no Renaissance mind could have anticipated. A new high-fidelity simulation study led by researchers from Johns Hopkins University has demonstrated that the 15th-century design not only generates lift but does so with surprising efficiency and vastly reduced acoustic noise compared to modern drone rotors. Using state-of-the-art fluid dynamics and aeroacoustic modeling, the study delivers precise data on how da Vinci’s spiral-shaped flying machine performs in flight, and why its design holds unexpected advantages in today’s world of drones and surveillance technology.
The aerial screw, imagined by da Vinci in the late 1400s, was a spiral-shaped rotor meant to lift vertically by rotating rapidly. It was theorised to work on the same principle as a screw boring through air, converting rotary motion into lift. While commonly dismissed as a non-functional curiosity due to its human-powered constraints, the aerodynamic concept behind the spiral rotor had never been subjected to rigorous physical modeling until now. The new study, published in June 2025, applies direct numerical simulations to analyse the forces and sound emissions generated by a modernised reconstruction of the screw. By comparing the results to those from a standard two-blade rotor, the researchers were able to isolate performance differences and highlight the unique strengths of da Vinci’s design.
One of the core findings is that da Vinci’s aerial screw consumes significantly less mechanical power per unit of lift than its modern counterparts. Despite a lower lift coefficient and an overall less compact design, the screw rotor’s large surface area allows it to operate at lower rotational speeds. This results in less energy expenditure and, crucially, far less noise. Acoustic intensity scales with the square of rotational speed, meaning that slower spinning rotors naturally emit quieter signatures. In tests simulating flight conditions at Reynolds numbers of 2000, 4000, and 8000, the aerial screw consistently outperformed the standard rotor in both power efficiency and aeroacoustic emissions, particularly in the low-lift regimes relevant to small drone platforms.
The aerodynamic analysis revealed two distinct regions of effective lift generation on the aerial screw. One occurs near the top leading edge, where the spiral initiates its ascent, and the other emerges lower along the spiral where tip velocities are still high. While large sections of the rotor surface contribute little to net lift, the design’s continuous spiral shape introduces a crucial advantage: the elimination of blade–vortex interaction. This is a major source of noise in conventional multi-blade rotorcraft, where vortices shed from one blade collide with those from another. Da Vinci’s screw avoids this entirely, functioning more like a singular, uninterrupted wing that suppresses acoustic disturbances.
To generate accurate comparisons, the team constructed both the aerial screw and a canonical two-bladed rotor as thin membrane structures and simulated them in a controlled, rotating frame of reference. The canonical rotor featured an angle of attack of 20 degrees and an aspect ratio of 5, representing a typical drone propeller. While the standard rotor produced higher lift per area due to its focused geometry and concentrated vortex structures, it required much higher RPMs and exhibited stronger broadband and tonal noise emissions across all directions.
When both designs were adjusted to generate equal amounts of lift—a crucial comparison for practical drone payloads—the aerial screw consistently demonstrated lower mechanical energy demands and substantially reduced sound profiles. At equal lift, the screw operated at 5000 RPM, while the canonical rotor required 7550 RPM. Acoustic monitoring conducted at a distance of ten rotor radii showed that the screw’s noise was lower in all directions, with diminished tonal peaks and faster broadband noise attenuation.
This distinction matters far beyond academic curiosity. In an era where drone noise is one of the most prominent objections to widespread deployment—particularly in urban environments and near sensitive wildlife habitats—the search for low-noise propulsion systems is gaining momentum. Traditional rotors, though highly efficient, generate signature sounds that travel long distances and betray the drone’s presence. As applications shift toward quiet surveillance, parcel delivery, and close-quarters scientific operations, acoustic stealth is becoming a priority.
The aerial screw’s advantages extend into this domain precisely because of its inefficiencies in other contexts. Its large wetted area spreads lift production across a broader surface, lowering the speed needed to generate upward force. This in turn suppresses pressure fluctuations and sheds weaker vortices, softening the acoustic footprint. Even though much of the surface area is aerodynamically passive, the trade-off is a system that can carry comparable loads without the high-frequency whine of standard rotors.
Another important aspect of the study was its scaling analysis, which confirmed prior theoretical predictions: that increasing blade surface area while decreasing RPM yields both lower mechanical power consumption and reduced noise, as long as the lift coefficient does not degrade dramatically. While the aerial screw’s lift coefficient was substantially lower than the canonical rotor’s, its design remained within thresholds that allowed these benefits to emerge. This confirms that unconventional rotor geometries should not be dismissed out of hand, especially when secondary performance metrics like noise and energy use are prioritised over raw thrust.
The high-resolution simulations used in the study involved up to 32 million grid points for the highest Reynolds number cases, employing a fractional-step Navier-Stokes solver and immersed boundary techniques to resolve fluid interactions with zero-thickness membrane surfaces. Aeroacoustic predictions were derived from Brentner and Farassat’s formulation of the Ffowcs Williams-Hawkings equation, allowing accurate modeling of sound pressure fields over time and space. By using both near-field and far-field analysis, the study constructed full-spectrum acoustic profiles that can be directly translated into real-world expectations.
While the aerial screw is not likely to replace all modern rotor designs, it presents a serious candidate for niche applications where noise matters more than compactness or maximum thrust. Small surveillance drones, indoor reconnaissance bots, and airborne sensors operating in populated or wildlife-sensitive areas could benefit immensely from adopting spiral-based rotors. There is also potential for hybrid designs, where elements of the aerial screw are merged with multi-blade layouts to optimise both lift and noise profiles.
One key takeaway is the validation of da Vinci’s original concept. While the human-powered design was impractical, his core intuition—that a spiral rotating structure could generate vertical lift by compressing and redirecting air—was accurate. More than five centuries after the sketch was drawn, direct numerical evidence now supports the physical viability of the machine. This is more than a historical footnote. It is a reminder that radically different approaches, even those long ignored, may hold the keys to solving modern engineering problems.
In its full configuration, the da Vinci screw used in the study was scaled to have a base radius of 0.152 metres, a top radius of half that, and a pitch ratio of 1.31. These proportions were informed by previous optimisation studies on spiral propellers. When compared under iso-lift conditions, the aerial screw matched the canonical rotor in total lift output but consumed only 58 percent of the mechanical power and emitted just 28 percent of the acoustic intensity per unit lift. This disparity grew even more pronounced in the lower-lift scenarios common to micro-drones, where the screw outperformed the standard rotor by orders of magnitude in noise reduction.
The research team acknowledged that further work is needed to test the design at higher Reynolds numbers, as real-world drone applications often operate at values in the hundreds of thousands. Simulations at this scale would require turbulence modeling approaches and additional consideration of structural integrity, dynamic stability, and material response. The thin-membrane model used in this study served to isolate aerodynamic principles, but practical deployment would require robust materials and possibly active controls to stabilise the large surface area in fluctuating conditions.
Even so, the data provides an engineering baseline for what might have once been considered fantasy. The aerial screw is no longer a flight of imagination. It is a verified low-power, low-noise rotor system with clear advantages in specific domains. With growing public demand for quieter skies and greater energy efficiency in autonomous platforms, the time may be right for engineers to look backward in order to move forward.
Source:
Prakhar, S., Seo, J.-H., & Mittal, R. (2025). Aerodynamics and Aeroacoustics of da Vinci’s Aerial Screw. arXiv preprint arXiv:2506.10223v1. https://arxiv.org/abs/2506.10223
ChristopherBlackwell
Hey, that's pretty cool how his design, over 5 centuries old can best modern designs
on June 28, 2025, 6:23 pm
