It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
A group of Japanese researchers, who published their findings in IOP Publishing's Bioinspiration & Biomimetics, have succeeded in building a fully functional replica model - an ornithopter - of a swallowtail butterfly, and they have filmed their model butterfly flying.
Among the various types of butterflies, swallowtails are unique in that their wing area is very large relative to their body mass. This combined with their overlapping fore wings means that their flapping frequency is comparatively low and their general wing motion severely restricted.
As a result, swallowtails' ability to actively control the aerodynamic force of their wings is limited and their body motion is a passive reaction to the simple flapping motion, and not - as common in other types of butterfly - an active reaction to aerodynamics.
To prove that the swallowtail achieves forward flight with simple flapping motions, the researchers built a lifelike ornithopter in the same dimensions as the butterfly, copying the swallowtail's distinct wing shape and the thin membranes and veins that cover its wings.
Using motion analysis software, the researchers were able to monitor the ornithopter's aerodynamic performance, showing that flight can be realised with simple flapping motions without feedback control, a model which can be applied to future aerodynamic systems.
Engineers Hiroto Tanaka and Isao Shimoyama of Harvard University and University of Tokyo, respectively, created the tiny butterfly to try to understand the biomechanics of butterfly flight.
But the tiny machine may not teach us too much about how butterflies actually row through the air, said Robert Dudley, a physiologist at the University of California, Berkeley, co-author of the research to be published May 20 in the journal Bioinspiration & Biomimetics.
“As a technical accomplishment, this work is impressive, but there are a number of aerodynamic and biological issues that need further attention,” Dudley wrote in an e-mail to Wired.com.
Butterfly flight is somewhat mysterious because it’s roughly the opposite of “as the crow flies.” Butterflies flit about rather than flying in a straight line. That actually costs them more energy, Dudley said, so scientists assume their looping flying serves some evolutionary purpose.
“The advantage is that it’s thought to be an anti-predator behavior,” Dudley said. “The claim is that irregular flight paths are a permanent signal of prey unprofitability.”
Would-be predators presumably take one look at the chaotic, loopy butterfly flight and decide to go after easier to predict snacks.
The Japanese researchers somewhat capture this oscillating type of flight with their plastic-winged flyer, but Dudley argued that the differences between the bot and a real butterfly are so great as to invalidate the biological lessons the researchers try to draw.
“There is nothing fundamentally wrong with this approach but it severely limits any claims to the biology,” Dudley said.