When birds fly, their wings generate circular currents of air called vortices. The precise behaviour of these vortices can tell scientists a great deal about how birds use their wings in flight. But until recently it hasn't been possible to study them. This is because the perfect way to measure the currents is by using a laser but the laser could blind the bird that is flying through the beam.
Lasers and Wind Tunnels
It is possible to see airflow using a laser sheet in a wind tunnel. Particles can be released into the tunnel and these then move with the airflow created. The laser illuminates them and when a bird flies through them, it will disrupt the particles. Scientists can then see exactly what is happening to the air when the bird is in flight.
How frustrating must it have been for the scientists? They knew exactly how to study bird flight but couldn't proceed because they risked blinding the bird that they were studying. What could they do to solve the problem?
The solution was to create a miniature pair of goggles for a bird! If the researchers could a find a bird who was willing to wear them and then fly into a laser sheet, that is! But then some birds will do amazing things for a bit of seed!
A white parrotlet proved willing to wear the goggles. Parrotlets are a genus of parrots which are small in size and native to South America. These diminutive birds are known for being intelligent and characterful.
The special goggles were 3D printed and featured the same type of lens that the scientists use themselves. The bird was acclimatised to wearing the goggles and then researchers at Stanford University filmed the little chap using high speed video whilst he flew through the particles in the wind tunnel. This enabled them to observe the wing tip vortices.
The researchers discovered that the little tornados of air created by the beating wings broke down after only three wing beats and this was a surprise. The experiment has shown that we did not have a proper understanding of how birds fly. The new information could help engineers to build more efficient aeroplanes.
We may have a parrotlet to thank for future developments in aviation.