Researchers from the City, University of London have found that the microstructures on owl feathers, called finlets, could lead to silent flight.

The team was inspired by the complex 3D geometry of the extensions along the front of owl feathers. The geometry has been reconstructed in previous studies using high-resolution micro CT scans, which are then transferred to a digital shape model.

Owl wingspan. Source: Professor Hermann Wagner

During the study, the team translated detailed 3D geometry data of typical owl feathers into a biomimetic aerofoil and studied their aerodynamic effect.

The produced owl feathers underwent flow simulations to study the aerodynamic function of the finlets. This effect stabilized the flow over a swept wing aerofoil, which helps owls while they are flapping their wings and gliding. The researchers used flow studies in a water tunnel.

The results showed that the finlets coherently turned the flow direction and kept the air flowing longer, leading to more stability and allowing the owl to avoid turbulence during flight.

The team also found that finlets act like thin guide vanes because of their special 3D curvature. A regular array of finlets over a wingspan turns the owl’s flow direction away from an obstacle in a smooth and coherent way.

Researchers plan to use the technical realization of swept-wing aerofoil patterns in an anechoic wind tunnel for more acoustic testing. The outcome of this research could be used to reduce aircraft noise.

A paper on this technology was published in Bioinspiration and Biomimetics.