Stanford Bird Study Challenges Some Secrets of Flight

Leonardo DaVinci intensely studied birds more than 500 years ago trying to understand how they flew. Today, even after more than 100 years of the manned flight, a group of Stanford University graduate students studying the science of flight discovered we might not know quite as much about how birds generate lift as we once thought.

"The goal of our study was to compare very commonly used models in literature to figure out how much lift a bird or other flying animal generates based off its wake. But what we found was that all three models we tried were very inaccurate because they make assumptions that aren’t necessarily true,” said student Diana Chin in a story published this week by the university based on the work of mechanical engineer and assistant professor David Lentink.

The Stanford students allowed small birds, parrotlets, to fly through air infused with micro-sized aerosol particles that scattered when disturbed, with movement tracked by lasers. The birds were fitted with special tiny pairs of goggles to protect their eyes from particle damage.

Scientists use the results of these kinds of tests to better understand how flying creatures generate the lift needed to sustain flight at certain weights, data used to create various categories of drones and flying robots. Lentink's students have already created a wing-flapping robot that lands and takes off vertically.

In early tests, students uncovered the clearest picture to date of the critter-generated wingtip vortices that experts assumed remained relatively steady much like the contrails following an airplane. Instead, they found the bird-tip vortices break up in a very dramatic fashion. Lentink said this research represents a new starting point to better understand how birds like their parrotlet really fly.

Watch the Stanford students' experiment below.