Researchers studying flight at Stanford University recently used a novel method to debunk popular flight models: birds wearing tiny goggles flying through lasers.
Eric Gutierrez, a former graduate student at Lentink lab and lead author of the study, wanted to measure the vortex (or vortices) that a bird created in flight. In order to do that, the bird, a parrotlet named Obi, would have to fly through a pane of lasers that lit up the movement of microparticles in the air.
“We would never do this ourselves, we would never walk through a laser sheet without having any protection,” said David Lentink, assistant professor of mechanical engineering. “So we really had to think about, ‘How can we protect our birds?’”
Gutierrez’s goggles were the answer.
The researchers cut out the lenses from their own protective goggles, 3D printed the sockets and painted them black and used special veterinary straps. And in order to prevent the goggles from slipping, they applied a very thin layer of shaving cream to the inside of the straps.
Obi was trained to wear the tiny laser goggles and fly from perch to perch, between which the sheet of lasers was placed.
Co-author Diana Chin said the results showed that the three popular flight models were inaccurate.
“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,” she said. “What we found was that all three models we tried out were very inaccurate because they make assumptions that aren’t necessarily true.”
This surprised the researchers. According to them, previous research had assumed the vortices created by flapping wings remained “relatively frozen over time.”
Speaking to Global News, Lentink said they observed that the vortex at the tips of each of Obi’s wings broke down, which they did not expect.
“We showed that when the vortices break up, even the best performing models have a hard time accounting for lift,” he said, adding that one model predicted that the bird would be in free fall when in reality it was flying.
As if tiny parrots wearing custom laser-proof goggles weren’t quirky enough, this research has implications on flying robots – at least that’s what the Lentink lab is going to apply it to.
Lentink said most studies on animal flight have been used to generate data precise enough to create more effective aerial robots, such as drones or robots with flapping wings.