Coating aeroplane wings with a feather-like material could combat
drag and therefore save fuel, according to researchers at the
University of Genoa.
The team has published a paper claiming that synthetic feathers
could improve the efficiency of vehicles that travel through the air or
under water.
"Many efficient locomotion techniques are found in nature, as they
have survived the tests of evolution over millions of years and reached
a high level of adaptation," Alessandro Bottaro wrote in the Journal of Fluid Mechanics.
"One interesting example is the feathers over the wings of birds. Even
though it is difficult to monitor their dynamics due to the animal’s
rapid motion, they are believed to play a crucial role in the
aerodynamics of birds."
Researchers looked
at the six different types of feathers that cover birds’ bodies,
including smaller feathers, called coverts, which stick up at right
angles to the bird’s wings during gliding and vibrate in the airflow,
according to New Scientist.
To
test the effects of these feathers, Bottaro and his team created a 20cm
diameter computer model cylinder. They covered it in rigid keratin
bristles 4-6cm long and 0.5mm in diameter at a density of around three
fibres per square centimetre, then put it in a virtual wind tunnel.
The
team found that "the coating is capable of increasing global
aerodynamics performance" of the cylinder, reducing drag by up to 15
per cent.
The reason is that the bristles prevented the cylinder from creating
a slipstream, an area of low pressure that creates drag and turbulence
behind the wing of an aircraft. Bottaro says that this phenomenon also
explains why new tennis balls, covered in felt, will fly faster than
worn out ones.
Bottaro is now planning to see how the bristles
will perform "under turbulent conditions", taking into account the
range of weather conditions that aeroplanes encounter. He is confident
that the simulated feathers, which don’t "require any input of energy
to work", may well be a worthwile investment for airlines.
He acknowledges that one potential issue is cleaning. Birds'
feathers are kept clean and efficient by constant preening – aircraft
are less good at taking care of themselves.
