On Making Flapping Drones: Understanding How Butterflies Fly Will Be Helpful

Butterflies are fascinating insects, especially their colorful wings. Beyond its beauty, the wings of a butterfly also have its unique mechanism of operating for an optimal level of flight.

In the past, scientists believe that butterflies clap their wings to thrust forward. But Swedish scientists have now concluded that this motion is far more complex than it was previously imagined.

They said that butterflies flex their wings by making a pocket that traps more air and provides more propulsion that helps them takeoff. According to the researchers, this mechanism helps butterflies escape from their predators.

They also believe that understanding how butterflies fly will help improve the design of the flapping drones.

Butterflies Create Pockets to Aid Propulsion

Scientists found that butterflies do not just flap their wings when they fly. Instead, these insects create a pocket that traps more air to aid in propulsion. Biologist Per Henningsson of Lund University said that given the many predators of butterflies it is crucial for them to be quicker than them. So being able to take off as quickly as possible than others gives them an obvious advantage.

This mechanism of how butterflies fly is a strong selective pressure because it is a matter of life or death, according to Big World Tale. Some natural predators of butterflies include frogs, spiders, lizards, and birds.

Henningsson and fellow biologist Cristoffer Johansson also found that the butterflies perform this move "in a far more advanced way than we ever realized."

However, they are not sure whether the same pocket technique is employed while the butterfly is in free flight. But they are sure that this is used during the take-off phase and that butterflies tend to do it a lot.

The researchers decided to make mechanical wings that are based on the slow-motion video of the silver-washed fritillary flying. One set was made to be rigid, while the other pair is flexible wings, just like the wings of a real butterfly.

They noticed that the flexible mechanical wings are 28% more efficient and 22% better at generating force than the rigid mechanical wings, MailOnline reported.

"Although conventionally considered aerodynamically inefficient, butterfly wings could be ideally suited to form the pocket shape," Henningsson said.

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Improving Flapping Drones Design

Scientists believe that this discovery could help improve the design of the flapping drones. In 2020, engineers from the University of South Australia had successfully created a four-winged bird-like drone that flaps to generate a forward thrust.

The flapping drone, called Ornithopters, can fly and move in ways that are unlike the existing drone configurations that mainly rely on propellers and static wings. The Ornithopters are inspired by the wings of hummingbirds and insects. The engineers believed that their flapping drone could outperform the conventional drones using this technology, Science Times reported.

But Henningsson believes that the design of ornithopters could be significantly improved if the pocket technique of butterflies will also be applied to the flapping bird.

"The people that are working on these designs ... should look into this cup-shape behavior, since there [is] lots of efficiency and effectiveness to be gained from it," Henningsson said.