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 email@example.com
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
Cancer diagnosis: no more needles?
25.05.2018 | Christian-Albrechts-Universität zu Kiel
Less is more? Gene switch for healthy aging found
25.05.2018 | Leibniz-Institut für Alternsforschung - Fritz-Lipmann-Institut e.V. (FLI)
The more electronics steer, accelerate and brake cars, the more important it is to protect them against cyber-attacks. That is why 15 partners from industry and academia will work together over the next three years on new approaches to IT security in self-driving cars. The joint project goes by the name Security For Connected, Autonomous Cars (SecForCARs) and has funding of €7.2 million from the German Federal Ministry of Education and Research. Infineon is leading the project.
Vehicles already offer diverse communication interfaces and more and more automated functions, such as distance and lane-keeping assist systems. At the same...
A research team led by physicists at the Technical University of Munich (TUM) has developed molecular nanoswitches that can be toggled between two structurally different states using an applied voltage. They can serve as the basis for a pioneering class of devices that could replace silicon-based components with organic molecules.
The development of new electronic technologies drives the incessant reduction of functional component sizes. In the context of an international collaborative...
At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.
At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...
There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?
At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...
So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics
Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...
25.05.2018 | Event News
02.05.2018 | Event News
13.04.2018 | Event News
25.05.2018 | Event News
25.05.2018 | Machine Engineering
25.05.2018 | Life Sciences