If you're going to be working with lasers, you need to wear safety goggles. That's just common sense. And it's no less true if you're small and feathered.
Little parrotlet Obi, therefore, has his own set of custom-made safety goggles (made from human-sized ones) to protect his eyes when he flies through a laser sheet, as he has been trained to do.
Why is he doing so? So that researchers at Stanford University's Letink Lab can study how the air moves in the wake of a bird's flight. And it's thank to Obi, along with graduate students Eric Gutierrez and Diana Chin, and mechanical engineer David Letink, that we now know that there may be some faults in three flight models.
"The goal of our study was to compare very commonly used models in the literature to figure out how much lift a bird, or other flying animal, generates based off its wake," Chin said in a statement. "What we found was that all three models we tried out were very inaccurate because they make assumptions that aren't necessarily true."
To test the models, the team trained Obi to wear the goggles and fly from one perch to another. Then a laser sheet was seeded with non-toxic, aerosol-sized particles. As Obi flew through this laser sheet, the disturbed particles swirled into vortices left in his wake.
Previous models suggested that these vortices remain in place after the bird has passed through the air, much like aeroplane contrails, the team said. But their research found that bird vortices break up quickly and violently.
"Whereas vortex breakup happens far away behind the aircraft -- like more than a thousand metres -- in birds, it can happen very close to the bird, within two or three wingbeats, and it is much more violent," said senior author Letink.
The team also found that the models they tested did not accurately predict the lift generated by the parrotlet's wings. This research joins a growing body conducted by the lab across many different animals, including different bird species, bats and insects. The team hope it can be used to help develop flying robots that flap wings, rather than rely on rotors.
Will it be as adorable as Obi in his little goggles, though?