Most scientists who create models trying to understand the mechanics and aerodynamics of insect flight have assumed that insect wings are relatively rigid as they flap.
New University of Washington research using high-speed digital imaging shows that, at least for some insects, wings that flex and deform, something like what happens to a heavy beach towel when you snap it to get rid of the sand, are the best for staying aloft.
"The evidence indicates that flexible wings are producing profoundly different air flows than stiff wings, and those flows appear to be more beneficial for generating lift," said Andrew Mountcastle, a UW doctoral student in biology.
He used particle image velocimetry, a technique commonly used to determine flow velocities in fluids, to study how air flows over the wings of Manduca sexta, or tobacco hawkmoths. The method combined laser light and high-speed digital video to model air flow.
A hawkmoth's wings are controlled by muscles on the insect's body and have no internal muscles of their own. The bulk of the wing is something like fabric stretched back from a stiff leading edge, fabric that is elastic and bends from inertia as the wing accelerates or decelerates through each stroke.
To test the wings' function, they were attached to mechanical "flappers" that moved back and forth 25 times a second, the same frequency at which the moths flap their wings, with the focus on how the wings deformed with each motion reversal. While the machine placed the wings at the same dominant angle as in normal moth flight, it could only approximate natural motion in one axis of rotation, compared with the three axes controlled in actual moth flight.
For the research, wings were removed from moths and tested in the mechanical "flapper" immediately, while they maintained most of their natural elasticity. After that the wings were allowed to dry for 12 to 24 hours and covered with enough spray paint to restore their original mass, then the wings were tested again in their more rigid state. The high-speed video, when viewed in slow motion, provided graphic detail of how the wings deformed as they flapped.
"That gave us two profoundly different deformations when we flapped the wings at natural wing-beat frequencies," Mountcastle said.
The "fresh," or flexible, wings had a mean deformation of 1.6 millimeters (about 64-thousandths of an inch) for each of five motion reversals, while the dry, stiff wings had a mean deformation of 1.15 millimeters (about 46-thousandths of an inch). By comparison, a freely hovering moth had a mean deformation of 1.52 millimeters (about 61-thousandths of an inch).
"Our results show that the flexible wings are doing a better job of generating lift-favorable momentum than are the stiff wings. They also are inducing airflow with greater overall velocity, which suggests the production of greater force for flight," Mountcastle said.
He is the lead author of a paper on the work, published in May in the journal Experiments in Fluids. Co-author is Thomas Daniel, a UW biology professor. The work was funded by the Defense Advanced Research Projects Agency, the National Science Foundation and the Joan and Richard Komen Endowed Chair.
"As a biologist, I am interested in the evolutionary implications of what we see here. To understand the selective pressures that have acted on wings through their evolution, we have to understand the functional implication of wing forms and their material properties," Mountcastle said.
He noted that insect wings have a wide variety of shapes and functions, and trying to understand how such diversity came about "is a really interesting biological question."
"There also is interest in developing tiny insect-like flapping robots, and certainly these results are relevant to that field," he said.
For more information, contact Mountcastle at 206-543-7335 or firstname.lastname@example.org
A high-resolution image and a video of hawkmoth research are available through this release at uwnews.washington.edu. Videos of research involving other insects can be viewed at http://students.washington.edu/mtcastle/movies.php.
Vince Stricherz | Newswise Science News
Researchers identify potentially druggable mutant p53 proteins that promote cancer growth
09.12.2016 | Cold Spring Harbor Laboratory
Plant-based substance boosts eyelash growth
09.12.2016 | Fraunhofer-Institut für Angewandte Polymerforschung IAP
Physicists of the University of Würzburg have made an astonishing discovery in a specific type of topological insulators. The effect is due to the structure of the materials used. The researchers have now published their work in the journal Science.
Topological insulators are currently the hot topic in physics according to the newspaper Neue Zürcher Zeitung. Only a few weeks ago, their importance was...
In recent years, lasers with ultrashort pulses (USP) down to the femtosecond range have become established on an industrial scale. They could advance some applications with the much-lauded “cold ablation” – if that meant they would then achieve more throughput. A new generation of process engineering that will address this issue in particular will be discussed at the “4th UKP Workshop – Ultrafast Laser Technology” in April 2017.
Even back in the 1990s, scientists were comparing materials processing with nanosecond, picosecond and femtosesecond pulses. The result was surprising:...
Have you ever wondered how you see the world? Vision is about photons of light, which are packets of energy, interacting with the atoms or molecules in what...
A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.
Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...
In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.
“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...
16.11.2016 | Event News
01.11.2016 | Event News
14.10.2016 | Event News
09.12.2016 | Life Sciences
09.12.2016 | Ecology, The Environment and Conservation
09.12.2016 | Health and Medicine