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The beautiful science of a butterfly's flight

Watch a video about Tiras Lin's research with painted lady butterflies »

The painted lady butterfly, with intricate orange, black and white markings resembling those of the more well-known monarch, flies with a grace that matches its beauty. It flutters through narrow passages, avoiding obstacles, changing directions, then lands softly, effortlessly.

Tiras Lin, an undergraduate at the Whiting School of Engineering, has discovered that the secret to flying like a butterfly is in minute mid-air adjustments imperceptible to the human eye. By filming and analyzing the butterfly's movements, Lin has gained insight into precisely how it moves in flight.

The research is funded by U.S. defense agencies that support the development of insect-sized drone aircraft that could carry out reconnaissance, search-and-rescue and environmental monitoring missions for the military without risking human lives. These devices are commonly called micro aerial vehicles, or MAVs.

"For military missions in particular, these MAVs must be able to fly successfully through complex urban environments, where there can be tight spaces and turbulent gusts of wind," Lin says. "These flying robots will need to be able to turn quickly. But one area in which MAVs are lacking is maneuverability."

In an effort to better understand aerial maneuverability, Lin looks to butterflies, which beat their wings about 25 times per second and engage in a variety of rapid twists and turns while in flight.

"Flying insects are capable of performing a dazzling variety of flight maneuvers," he says. "In designing MAVs, we can learn a lot from flying insects."

Lin and his team—his work is supervised by Rajat Mittal, a professor of mechanical engineering, and he works closely with graduate student Lingxiao Zheng—use high-speed, high-resolution cameras to help them document the flight of the butterflies in detail. By viewing footage from three fixed cameras, each capable of recording 3,000 one-megapixel images per second, the team can evaluate changes in trajectory and direction, and determine how these maneuvers are achieved.

What they discovered is that a previous assumption about the flight dynamics of insects is inaccurate, a finding that could assist MAV designers and also has implications for biologists who study how insects fly.

Lin recently presented some of his findings at the annual meeting of the American Physical Society's Division of Fluid Dynamics. The junior from San Rafael, Calif., also won second prize for his research presentation at a regional meeting of the American Institute of Aeronautics and Astronautics.

Now Lin is looking into even smaller insects. With the support of the Johns Hopkins Provost's Undergraduate Research Awards program and under Mittal's guidance, he has started capturing footage of fruit flies, hoping to solve the mystery of how they land upside down on perches.

"This research is important because it attempts to not only address issues related to bio-inspired design of MAVs," Mittal says, "but it also explores fundamental questions in biology related to the limits and capabilities of flying insects."

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