Forum für Wissenschaft, Industrie und Wirtschaft

Hauptsponsoren:     3M 


Engineer Looks to Dragonflies, Bats for Flight Lessons

Ever since the Wright brothers, engineers have been working to develop bigger and better flying machines that maximize lift while minimizing drag.

There has always been a need to efficiently carry more people and more cargo. And so the science and engineering of getting large aircraft off the ground is very well understood.

But what about flight at a small scale? Say the scale of a dragonfly, a bird or a bat?

Hui Hu, an Iowa State University associate professor of aerospace engineering, said there hasn’t been a need to understand the airflow, the eddies and the spinning vortices created by flapping wings and so there haven’t been many engineering studies of small-scale flight. But that’s changing.

The U.S. Air Force, for example, is interested in insect-sized nano-air vehicles or bird-sized micro-air vehicles. The vehicles could fly microphones, cameras, sensors, transmitters and even tiny weapons right through a terrorist’s doorway.

So how do you design a little flier that’s fast and agile as a house fly?

Hu says a good place to start is nature itself.

And so for a few years he’s been using wind tunnel tests and imaging technologies to learn why dragonflies and bats are such effective fliers. How, for example, do flapping frequency, flight speed and wing angle affect the lift and thrust of a flapping wing?

Hu’s studies of bio-inspired aerodynamic designs began in 2008 when he spent the summer on a faculty fellowship at the Air Force Research Laboratory at Eglin Air Force Base in Florida. Over the years he’s published papers describing aerodynamic performance of different kinds of flapping wings.

A study based on the dragonfly, for example, found the uneven, sawtooth surface of the insect’s wing performed better than a smooth airfoil in the slow-speed, high-drag conditions of small-scale flight. Using particle image velocimetry – an imaging technique that uses lasers and cameras to measure and record flows – Hu found the corrugated wing created tiny air cushions that kept oncoming airflow attached to the wing’s surface. That stable airflow helped boost performance in the challenging flight conditions. By describing the underlying physics of dragonfly flight, Hu and Jeffery Murphy, a former Iowa State graduate student, won a 2009 Best Paper Award in applied aerodynamics from the American Institute of Aeronautics and Astronautics.

Another study of bat-like wings found the built-in flexibility of membrane-covered wings helped decrease drag and improve flight performance.

And what about building tiny flying machines that use flapping wings? Can engineers come up with a reliable way to make that work?

Hu has been looking into that, too.

He’s using piezoelectrics, materials that bend when subject to an electric current, to create flapping movements. That way flapping depends on feeding current to a material, rather than relying on a motor, gears and other moving parts.

Hu has also used his wind tunnel and imaging tests to study how pairs of flapping wings work together – just like they do on a dragonfly. He learned wings flapping out of sync (one wing up while the second is down) created more thrust. And tandem wings working side by side, rather than top to bottom, maximize thrust and lift.

Hu said these kinds of physics and aerodynamics lessons – and many more – need to be learned before engineers can design effective nano- and micro-scale vehicles.

And so he’s getting students immersed in the studies.

Hu has won a $150,000, three-year National Science Foundation grant that sends up to 12 Iowa State students to China’s Shanghai Jiao Tong University for eight weeks of intensive summer research. The students work at the university’s J.C. Wu Aerodynamics Research Center to study bio-inspired aerodynamics and engineering problems.

“We’re just now learning what makes a dragonfly work,” Hu said. “There was no need to understand flight at these small scales. But now the Defense Advanced Research Projects Agency and the Air Force say there is a need and so there’s an effort to work on it. We’re figuring out many, many interesting things we didn’t know before.”

Hui Hu, Aerospace Engineering, 515-294-0094,
Mike Krapfl, News Service, 515-294-4917,

Mike Krapfl | Newswise
Further information:

More articles from Machine Engineering:

nachricht Hardened steels for more efficient engines
23.11.2015 | Karlsruher Institut für Technologie (KIT)

nachricht Thick metal sheets for light ships: welding steel and aluminum
03.11.2015 | Laser Zentrum Hannover e.V.

All articles from Machine Engineering >>>

The most recent press releases about innovation >>>

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

Im Focus: Klimawandel: Forscher weisen dramatische Veränderung in den 1980er Jahren nach

Ende der 1980er Jahre erlebte die Erde eine dramatische Klimaveränderung. Sie umfasste die Tiefen der Ozeane ebenso wie die obere Atmosphäre und reichte vom Nord- bis zum Südpol. Ausgelöst durch den Ausbruch des Vulkans El Chichón in Mexico 1982 und verstärkt durch menschliches Handeln folgte daraus die größte Temperaturverschiebung der letzten 1.000 Jahre. Erstmals nachgewiesen hat dies ein internationales Forscherteam um Prof. Philip C. Reid von der Plymouth University und der Sir Alister Hardy Foundation for Ocean Science (UK). Die Ergebnisse wurden kürzlich in der Fachzeitschrift „Global Change Biology“ veröffentlicht.

Abrupte Klimaveränderungen haben oft dramatische Folgen für unseren Planeten. Dennoch sind sie in ihrer Art, ihrem Ausmaß und in ihrer Wirkungsweise meist nur...

Im Focus: Climate study finds evidence of global shift in the 1980s

Planet Earth experienced a global climate shift in the late 1980s on an unprecedented scale, fuelled by anthropogenic warming and a volcanic eruption, according to new research published this week.

Scientists say that a major step change, or ‘regime shift’, in the Earth’s biophysical systems, from the upper atmosphere to the depths of the ocean and from...

Im Focus: Innovative Photovoltaik – vom Labor an die Fassade

Fraunhofer ISE demonstriert neue Zell- und Modultechnologien an der Außenfassade eines Laborgebäudes

Das Fraunhofer-Institut für Solare Energiesysteme ISE hat die Außenfassade eines seiner Laborgebäude mit 70 Photovoltaik-Modulen ausgerüstet. Die Module...

Im Focus: Innovative Photovoltaics – from the Lab to the Façade

Fraunhofer ISE Demonstrates New Cell and Module Technologies on its Outer Building Façade

The Fraunhofer Institute for Solar Energy Systems ISE has installed 70 photovoltaic modules on the outer façade of one of its lab buildings. The modules were...

Im Focus: Follow Me: Forscher der Jacobs University steuern Unterwasser-Roboter erstmals durch Zeichensprache

Normalerweise werden Unterwasser-Roboter über lange Kabel von Booten oder von Land aus gesteuert. Forschern der Jacobs University in Bremen ist nun ein Durchbruch in der Mensch-Maschine-Kommunikation gelungen: Erstmals konnten sie einen Unterwasser-Roboter mit Hilfe von Gesten navigieren. Eine spezielle Kamera half dabei, die Zeichensprache in Befehle umzusetzen. Die Feldtests fanden im Rahmen des EU-geförderten Projektes CADDY „Cognitive Autonomous Diving buddy“ statt.

Archäologische Untersuchungen im Ozean und vergleichbare komplexe Forschungsprojekte unter Wasser sind auf die Unterstützung von Robotern angewiesen, um in...

Alle Focus-News des Innovations-reports >>>



im innovations-report
in Kooperation mit academics

Konzepte nutzergerechter Fahrerarbeitsplatzgestaltung

26.11.2015 | Veranstaltungen

Versammelter Sachverstand: Fachleute des Mess- und Eichwesens treffen sich in der PTB

26.11.2015 | Veranstaltungen

Fraunhofer-Kongress »Urban Futures«: 2 Tage in der Stadt der Zukunft

25.11.2015 | Veranstaltungen

Weitere VideoLinks >>>
Aktuelle Beiträge

Alles unter Kontrolle – Energieautarke RFID-Transponder in der Logistik

26.11.2015 | Verkehr Logistik

Konzepte nutzergerechter Fahrerarbeitsplatzgestaltung

26.11.2015 | Veranstaltungsnachrichten

Versammelter Sachverstand: Fachleute des Mess- und Eichwesens treffen sich in der PTB

26.11.2015 | Veranstaltungsnachrichten