August 23, 2017
They are among nature's best
fliers, spending most of their time in flight … now scientists have shed new
light on how swifts can glide with ease, whatever the weather. A new study
suggests that the aerodynamics of swifts' wings enable them to adapt
effortlessly to sudden changes in wind speed and direction.
The wings' crescent shape lessens
the effects of blustery conditions, helping to stabilise them as they glide
during turbulent weather, researchers say. This means swifts – which eat, mate
and even sleep on the wing – are not forced to use up vital energy to stay on
course.
Model wing
Scientists at Edinburgh
constructed a triangular model wing with the characteristic trailing edge shape
of swifts' wings. They studied its aerodynamic properties by fitting it into a
water flume that simulated airflow during flight. Using a laser sheet and a
digital camera, researchers tracked the movement of tiny glass balls in the
water, to reveal how air flows over the wing.
Results showed for the first time
that as air passes over the wing,
it can form into two or three circulating regions of airflow – known as
leading-edge vortices, or LEVs. In aircraft with triangle-shaped wings –
including Concorde – LEVs can generate extra lift, researchers say.
