Engineers are hoping new research showing owls can supress the vibrations that occur when they flap their wings can be used to help eliminate noise from structures such as wind turbines.
The research published in the Institution of Civil Engineers (ICE) Journal Bioinspired, Biomimetic and Nanobiomaterials, shows that even though owls have to use huge amounts of force to repeatedly flap their wings, they also have the capability to supress the vibrations caused when flapping.
It found that an owl’s feather structure can extract the mechanical energy from the vibrations and convert it into heat, meaning the owl remains quiet.
The study carried out in China and was led by Dalian University of Technology. It compared the Long Eared Owl, Golden Eagle and Pigeon primary feathers during flight, using laser displacement sensors and high speed cameras
Research leader Professor Jinkui Chu said: “Many owls have a unique and fascinating ability to fly so silently that they are out of their prey’s hearing range, due to their feather structure. This behaviour has long been of interest to engineers, as we seek to apply the owl’s noise-reduction mechanisms to other purposes and situations that benefit society.
“Now however, we know the owls’ silent flight ability is even more superior than we thought, you could say of all birds it is the ‘king of acoustic stealth’. It not only manages to suppress aerodynamic noise when gliding, but also mechanical noise caused by vibration during flying.
“This is remarkable, considering the sudden jumping, bending and twisting the wings are subjected to when flapping and the noise that creates for other birds. In the scientific world, the process used to eliminate this mechanical noise is called ‘damping’ – which means the extraction of mechanical energy from a vibrating system usually by converting it into heat and allowing it to remain steady.
“Our research showed the Long Eared Owl has superior ‘damping’ skill - meaning it can remain mind-blowingly stable and eliminate mechanical noise caused by the movement of its feathers – quite a feat of engineering.
“This study will hopefully provide further insight into the owls’ silent flight mechanism and help engineers develop ideas for special materials or structures - such as on-shore wind turbines -where similar noise elimination can be applied.”