Bats’ flight technique could lead to better drones

Long-eared bats are assisted in flight by their ears and body, according to a study by researchers at Lund University in Sweden. The recent findings improve researchers’ understanding of the bats’ flying technique and could be significant for the future development of drones, among other things.

Watch and embed video with researcher Christoffer Johansson

Contrary to what researchers have previously thought, Christoffer Johansson Westheim and his colleagues at Lund University can now show that long-eared bats are helped in flight by their large ears.

“We show how the air behind the body of a long-eared bat accelerates downwards, which means that the body and ears provide lift. This distinguishes the long-eared bats from other species that have been studied and indicates that the large ears do not merely create strong resistance, but also assist the animal in staying aloft”, says Christoffer Johansson Westheim.

The findings entail a greater understanding of the flight technique of bats. They also highlight the evolutionary conflict between flying as efficiently as possible and eco-locating, i.e. discovering objects by sending out soundwaves and perceiving the resulting echoes.

Another discovery made during the experiments and never previously described in research is how the bats generate forward motion when flying slowly. The forward motion is generated when the wings are held high and away from the body at the end of each beat.

“This specific way of generating power could lead to new aerodynamic control mechanisms for drones in the future, inspired by flying animals”, says Christoffer Johansson Westheim.

The experiments were conducted in a wind tunnel in which trained bats flew through thin smoke to reach a stick with food on it. Meanwhile the researchers aimed a laser beam at the smoke behind the bats and took pictures of the illuminated smoke particles. The researchers measured how the smoke moved to calculate the forces generated by each beat of the bats’ wings.

The article is published in the research journal Scientific Reports.

Additional material
Watch and embed video with Christoffer Johansson

Video with long-eared bats flying in the wind tunnel

Article
Johansson C, et al (2016) Ear-body lift and a novel thrust generating mechanism revealed by the complex wake of brown long-eared bats (Plecotus auritus). Scientific Reports.

For more information
Christoffer Johansson Westheim, senior lecturer
Lund University, Department of Biology
Tel: + 46 46 222 49 55
Email: christoffer.johansson@biol.lu.se

Lund University was founded in 1666 and is regularly ranked as one of the world’s top 100 higher education institutions. The University has 41 000 students and 7 500 staff based in Lund, Helsingborg and Malmö. We are united in our efforts to understand, explain and improve our world and the human condition.