Flying animals are able to execute unique and remarkable maneuvers because of specialized wings. Bats are considered to have one of the most impressive flight controls, thanks to the controlled joints that give the ability to adjust the wing shape to a specific area and angle of attack.
While bats are listed in the ranks of the most efficient flyers, their wings are also said to be among the heaviest. Bat wings are comprised of multiple bones and large muscles, thus, the ratio of the wing mass and body mass of bats are bigger than other flying animals.
The inertia or steady state in bat wings is commonly related to low aerial maneuverability but a group of researchers was able to demonstrate otherwise in a new study.
"Bats land in a unique way," said Sharon Swartz, senior author of the study and a biologist at Brown University. She further explained that bats have to change movements from flying with the heads forward to then execute an acrobatic stunt that involves putting its head down and feet up – something that no other flying animal can do.
The manner in which bats are able to produce the required force to exhibit the maneuvers has yet to be clearly established.
In a new research led by Attila Bergou, the authors trained two species of bats to fly into an enclosed space and land on a small mesh attached to the ceiling. High-speed cameras were installed to capture even the tiniest wing movements the bats make at a fraction of a second prior to landing.
The videos showed that as the bats come near the ceiling, they retracted one of their wings ever so minimal toward the body while the other full-extended wing flapped vigorously. With every asymmetric beat, the bats were seen making a half turn before they land on the mesh, feet first.
In another test, the researchers removed the mesh hence, the bats had nothing to hold on to. The videos showed the bats, while attempting to land, performed the same rolling maneuver using their wings in order to reestablish a forward flight.
The authors then utilized computer simulations to confirm if the observed effects were brought about by inertia instead of aerodynamics. They then used motion capture to document the movements and relayed the shots via computer simulations, which enabled researchers to switch different forces on and off. When the aerodynamic forces were turned off, the simulations still showed the same movements.
In another simulation, the authors decreased the mass of the bat wings relative to that of the fruit flies. The investigation showed that it is impossible to execute the same rotating maneuver upon landing without aerodynamic forces.
"What this tell us is that in bats, with their heavy wings, it's the inertial forces that are more important relative to aerodynamics," said Kenny Breuer, one of the study's senior authors. The weighty wings prove to have some benefits in bats.
The study was published in the journal PLOS Biology on Monday, Nov. 16.
