Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Wind tunnel experiments award flight certificate to bats

29.02.2008
What’s the similarity between a bumblebee and a hummingbird? None – apart from one thing: neither the bumblebee nor the hummingbird should be ebale to fly according to classic wing theory. Yet, this is what they do for a living.

In 1995 the conundrum of bumblebee flight got its final solution. And this week the aerodynamics of a hovering bat species has been revealed. Its flight was studied in the wind tunnel laboratory of Lund University, and the results are published in the prestigious journal Science.

The wind tunnel at Lund University is specially crafted for research on bird flight. Birds fly “at the spot” against a headwind, allowing detailed investigation of wing movements using high speed video cameras. It’s also possible to visualize the vortices around the wings and in the wake using fog as tracer particles.

In 2003 professor Anders Hedenström investigated the aerodynamics of bird flight using this method for the first time. In the spring 2007 his lab presented results from applying this method to flying bats for the first time. A nectar-feeding bat species, Palla’s long-tongued bat, was trained to visit a feeder in the wind tunnel. By varying the speed between 0 m/s (hovering) to 7 m/s, different behaviors were studied.

... more about:
»Flight »Hedenström »Tunnel »vortices

"When we investigated the aerodynamics of our bats we discovered that the wings generated more lift than they should at the slowest speeds (as dictated by classic wing theory),"says professor Hedenström.

"We recorded vortices shed in the wake, which we know well from our previous studies on birds. Now, our new study show that a stable leading edge vortex (LEV) is developed on top of the wing, and this vortex adds significant amounts of lift. Such vortices were previously known in insects, for example in bumblebees, and it was the discovery of leading edge vortices that finally resolved the bumblebee flight conundrum."

How can the bats generate such high lift? One of the team members and lead author of the new study, Florian Muijres, explains:

"The high lift arises because the bats can actively change the shape (curvature) by their elongated fingers and by muscle fibers in their membranous wing. A bumblebee cannot do this; its wings are stiff. This is compensated for by the wing-beat frequency. Bats beat their wings up to 17 times per second while the bumblebee can approach 200 wing-beats per second."

The paper in Science is: Leading-Edge Vortex Improves Lift in Slow-Flying Bats, authors are F T Muijres, L C Johansson, R Barfield, M Wolf, G R Spedding and A Hedenström.

Image legends:
The bats are highly maneuverable and can make quick turns during flights
http://www.naturvetenskap.kanslimn.lu.se/bataction.jpg
(Photo: L C Johansson, M Wolf, A Hedenström)
Vortex system on the bat’s wings – it is the vortex along the leading edge that is now described for the first time

http://www.naturvetenskap.kanslimn.lu.se/BoW/GF/bat_vortex_pattern.tif

Ingela Björck | alfa
Further information:
http://www.lu.se

Further reports about: Flight Hedenström Tunnel vortices

More articles from Life Sciences:

nachricht The secret sulfate code that lets the bad Tau in
16.07.2018 | American Society for Biochemistry and Molecular Biology

nachricht Colorectal cancer risk factors decrypted
16.07.2018 | Max-Planck-Institut für Stoffwechselforschung

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First evidence on the source of extragalactic particles

For the first time ever, scientists have determined the cosmic origin of highest-energy neutrinos. A research group led by IceCube scientist Elisa Resconi, spokesperson of the Collaborative Research Center SFB1258 at the Technical University of Munich (TUM), provides an important piece of evidence that the particles detected by the IceCube neutrino telescope at the South Pole originate from a galaxy four billion light-years away from Earth.

To rule out other origins with certainty, the team led by neutrino physicist Elisa Resconi from the Technical University of Munich and multi-wavelength...

Im Focus: Magnetic vortices: Two independent magnetic skyrmion phases discovered in a single material

For the first time a team of researchers have discovered two different phases of magnetic skyrmions in a single material. Physicists of the Technical Universities of Munich and Dresden and the University of Cologne can now better study and understand the properties of these magnetic structures, which are important for both basic research and applications.

Whirlpools are an everyday experience in a bath tub: When the water is drained a circular vortex is formed. Typically, such whirls are rather stable. Similar...

Im Focus: Breaking the bond: To take part or not?

Physicists working with Roland Wester at the University of Innsbruck have investigated if and how chemical reactions can be influenced by targeted vibrational excitation of the reactants. They were able to demonstrate that excitation with a laser beam does not affect the efficiency of a chemical exchange reaction and that the excited molecular group acts only as a spectator in the reaction.

A frequently used reaction in organic chemistry is nucleophilic substitution. It plays, for example, an important role in in the synthesis of new chemical...

Im Focus: New 2D Spectroscopy Methods

Optical spectroscopy allows investigating the energy structure and dynamic properties of complex quantum systems. Researchers from the University of Würzburg present two new approaches of coherent two-dimensional spectroscopy.

"Put an excitation into the system and observe how it evolves." According to physicist Professor Tobias Brixner, this is the credo of optical spectroscopy....

Im Focus: Chemical reactions in the light of ultrashort X-ray pulses from free-electron lasers

Ultra-short, high-intensity X-ray flashes open the door to the foundations of chemical reactions. Free-electron lasers generate these kinds of pulses, but there is a catch: the pulses vary in duration and energy. An international research team has now presented a solution: Using a ring of 16 detectors and a circularly polarized laser beam, they can determine both factors with attosecond accuracy.

Free-electron lasers (FELs) generate extremely short and intense X-ray flashes. Researchers can use these flashes to resolve structures with diameters on the...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Leading experts in Diabetes, Metabolism and Biomedical Engineering discuss Precision Medicine

13.07.2018 | Event News

Conference on Laser Polishing – LaP: Fine Tuning for Surfaces

12.07.2018 | Event News

11th European Wood-based Panel Symposium 2018: Meeting point for the wood-based materials industry

03.07.2018 | Event News

 
Latest News

Nano-kirigami: 'Paper-cut' provides model for 3D intelligent nanofabrication

16.07.2018 | Physics and Astronomy

New players, standardization and digitalization for more rail freight transport

16.07.2018 | Transportation and Logistics

Researchers discover natural product that could lead to new class of commercial herbicide

16.07.2018 | Agricultural and Forestry Science

VideoLinks
Science & Research
Overview of more VideoLinks >>>