Bats' flight technique could lead to better drones

Date: May 4, 2016

Source: Lund University

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.

Contrary to what researchers previously assumed, Christoffer Johansson Westheim and his colleagues at Lund University 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.

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The secret of dragonflies' flight

Date:

November 24, 2014

Source:

American Physical Society's Division of Fluid Dynamics

Summary:

Dragonflies can easily right themselves and maneuver tight turns while flying. Each of their four wings is controlled by separate muscles, giving them exquisite control over their flight. Researchers are investigating the physics behind this ability by recording high-speed video footage of dragonflies in flight and integrating the data into computer models.

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How neurons in bats' brains ensure a safe flight

Date:

September 1, 2014

Source:

Technische Universitaet Muenchen

Summary:

Bats emit ultrasound pulses and measure the echoes reflected from their surroundings. They have an extremely flexible internal navigation system that enables them to do this. A study shows that when a bat flies close to an object, the number of active neurons in the part of a bat's brain responsible for processing acoustic information about spatial positioning increases. This information helps bats to react quickly and avoid obstacles.

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Tiny muscles help bats fine-tune flight, stiffen wing skin

Date:

May 23, 2014

Source:

Brown University

Summary:

Bats appear to use a network of hair-thin muscles in their wing skin to control the stiffness and shape of their wings as they fly, according to a new study. The finding provides new insight about the aerodynamic fine-tuning of membrane wings, both natural and human-made.

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The way bats fly may inspire a new small flying vehicle of the future

By exploring how creatures in nature are able to fly by flapping their wings, researchers at Virginia Tech in the US hope to apply that knowledge in designing small flying machines known as "micro air vehicles" with flapping wings.

More than 1,000 species of bats have hand membrane wings, meaning that their fingers are essentially "webbed" and connected by a flexible membrane. But understanding how bats use their wings to manipulate the air around them is extremely challenging.

In Virginia Tech's study of fruit bat wings, the researchers used experimental measurements of the movements of the bats' wings in real flight, and then employed analysis software to see the direct relationship between wing motion and airflow around the bat’s wing. They have reported their findings in the journal Physics of Fluids.

Read on

The Secrets of a Bug's Flight

Nov. 12, 2013 — Researchers have identified some of the underlying physics that may explain how insects can so quickly recover from a stall in midflight -- unlike conventional fixed wing aircraft, where a stalled state often leads to a crash landing. 

The analysis, in which the researchers studied the flow around a rotating model wing, improves the understanding of how insects fly and informs the design of small flying robots built for intelligence gathering, surveillance, search-and-rescue, and other purposes. The work is described in the journal Physics of Fluids.

An insect such as a fruit fly hovers in the air by flapping its wings -- a complex motion akin to the freestyle stroke in swimming. The wing rotates in a single plane, and by varying the angle between the plane and its body, the insect can fly forward from a hovering position.

Read on

The Mathematical Butterfly: Simulations Provide New Insights On Flight

(ISNS) – Flapping and flitting butterflies have long inspired poets, singers and even boxers. Now their motions are inspiring researchers to understand how winged insects get from place to place.

"As the phrase 'float like a butterfly' shows, butterflies elegantly fly around," said study author Naoto Yokoyama, an assistant professor in aeronautics and astronautics at Kyoto University in Japan. "We would like to understand how they fly in the viewpoint of the fluid dynamics." 

Yokoyama and his colleagues created numerical simulations of a butterfly's forward flight. They modeled a chestnut tiger butterfly as four rigid bodies: a football-shaped thorax that lies between the head and the abdomen, the abdomen, and left and right thin, flat wings.

Continued: http://www.livescience.com/28951-the-mathematical-butterfly-simulations-provide-new-insights-on-flight.html

Neural Activity in Bats Measured In-Flight

Apr. 18, 2013 — Animals navigate and orient themselves to survive -- to find food and shelter or avoid predators, for example. Research conducted by Dr. Nachum Ulanovsky and research student Michael Yartsev of the Weizmann Institute's Neurobiology Department, published today in Science, reveals for the first time how three-dimensional, volumetric, space is perceived in mammalian brains. The research was conducted using a unique, miniaturized neural-telemetry system developed especially for this task, which enabled the measurement of single brain cells during flight.

The question of how animals orient themselves in space has been extensively studied, but until now experiments were only conducted in two-dimensional settings. These have found, for instance, that orientation relies on "place cells" -- neurons located in the hippocampus, a part of the brain involved in memory, especially spatial memory. Each place cell is responsible for a spatial area, and it sends an electrical signal when the animal is located in that area. Together, the place cells produce full representations of whole spatial environments. Unlike the laboratory experiments, however, the navigation of many animals in the real world, including humans, is carried out in three dimensions. But attempts to expand the scope of experiments from two to three dimensions had encountered difficulties.

One of the more famous efforts in this area was conducted by the University of Arizona and NASA, in which they launched rats into space (aboard a space shuttle). However, although the rats moved around in zero gravity, they ran along a set of straight, one-dimensional lines. Other experiments with three-dimensional projections onto two-dimensional surfaces did not manage to produce volumetric data, either. The conclusion was that in order to understand movement in three-dimensional, volumetric space, it is necessary to allow animals to move through all three dimensions -- that is, to research animals in flight.

Continued:  http://www.sciencedaily.com/releases/2013/04/130418142306.htm

How The Fly Flies

Max Planck scientists discover gene switch responsible for flight muscle formation
Flies are real flight artists, although they only have small wings compared to their body size. Scientists at the Max Planck Institute of Biochemistry in Martinsried near Munich, Germany, recently identified the genetic switch that regulates the formation of flight muscles. “The gene spalt is essential for the generation of the ultrafast super muscles,” emphasizes Frank Schnorrer, head of the research group “Muscle Dynamics”. “Without spalt, the fly builds only normal leg muscles instead of flight muscles.” The scientists’ results have now been published in Nature.

In order to fly efficiently, flies have to flap their small wings very fast. This causes the familiar buzzing and humming of the small beasts. The fruit fly Drosophila melanogaster moves her wings at a frequency of 200 hertz – that means its flight muscles contract and relax 200 times per second. “In contrast, a hundred meters sprinter who moves his legs only a few times per second moves like a snail,” Frank Schnorrer describes. How can the fruit fly flap its wings at such a high frequency?

Muscles control all body movements, including the wing oscillations. However, flight muscles are unique. Their contractions are not only regulated by nerve impulses as usual, but additionally triggered by tension. Every fly has two categories of flight muscles which enable the wing oscillations: One type moves the wings down and, at the same time, stretches the other type which induces its contraction. Such, the wings are pulled up again and stable wing oscillations begin.

Read more here ...

Pterosaur reptile used "pole vault" trick for take-off

Some have suggested the biggest pterosaurs were incapable of flight


A new study claims that the ancient winged reptiles known as pterosaurs used a "pole-vaulting" action to take to the air.

They say the creatures took off using all four of their limbs.

The reptiles vaulted over their wings, pushing off first with their hind limbs and then thrusting themselves upwards with their powerful arm muscles - not dissimilar to some modern bats.

The research is published in the open-access journal Plos One.

Pterosaurs lived at the same time as the dinosaurs, but belonged to a different group of reptiles. They existed from the Triassic Period until the end of the Cretaceous - about 220 million years ago to 65 million years ago.

In their study, Dr Mark Witton at Portsmouth University, UK, and Dr Michael Habib of Chatham University, Pennsylvania, US, reappraised giant pterosaur fossils.

Their findings challenge other claims that the giant pterosaurs - such as Pteranodon and the largest azhdarchids - were not capable of flying.

'Too heavy'
Researchers have previously suggested that these creatures were too heavy to have taken to the skies.

There have also been doubts that the ancient reptiles could have taken off using the same action as birds.

"Most birds take off either by running to pick up speed and jumping into the air before flapping wildly, or if they're small enough, they may simply launch themselves into the air from a standstill," said Dr Witton.

"Previous theories suggested that giant pterosaurs were too big and heavy to perform either of these manoeuvres."

He added: "These creatures were not birds; they were flying reptiles with a distinctly different skeletal structure, wing proportions and muscle mass.

"They would have achieved flight in a completely different way to birds and would have had a lower angle of take off and initial flight trajectory."

Muscle bulk
The authors of the latest study suggest that, with up to 50kg of forelimb muscle, the creatures could easily have launched themselves into the air despite their massive size and weight.

Dr Habib explained: "Instead of taking off with their legs alone, like birds, pterosaurs probably took off using all four of their limbs.

"By using their arms as the main engines for launching instead of their legs, they use the flight muscles - the strongest in their bodies - to take off and that gives them potential to launch much greater weight into the air," he explained.

"When they were far enough off the ground, they could start flapping their wings before finding a thermal or another area of uplift to gain some altitude and glide off to wherever they wanted to go," he told BBC News.

The largest pterosaurs may have had wingspans up to 13m and weighed up to 544kg.

But the authors' reappraisal of pterosaur fossils suggests these numbers may have been overestimated. They argue that the biggest creatures may have had 10-11m wingspans and weighed between 200 and 250 kg.