Robothopter in biomimetic butterfly boffinry breakthrough
Scientific flap over flapless flapper
Vid Japanese aerobiomimetics boffins have developed a tiny ornithopter modelled on a swallowtail butterfly.
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According to Hiroto Tanaka and Isao Shimoyama, the team behind the diminutive flying flapper-bot, the fact that it flies is highly significant. The machine, like the butterfly it is modelled on, beats its wings in simple flapping motions without any fancy control inputs - rather as though it were an aeroplane without elevators, ailerons or flaps.
The two boffins write:
Unlike other flying insects, the wing motion of swallowtail butterflies is basically limited to flapping because their fore wings partly overlap their hind wings, structurally restricting the feathering needed for active control of aerodynamic force. Hence, it can be hypothesized that the flight of swallowtail butterflies is realized with simple flapping, requiring little feedback control of the feathering angle. To verify this hypothesis, we fabricated an artificial butterfly mimicking the wing motion and wing shape of a swallowtail butterfly and analyzed its flights using images taken with a high-speed video camera.
Other butterflies, whose bodies are heavier in relation to their wing area and whose wings are more easily articulated, exert much more active control over their flight surfaces. To date most ornithopter research has focused on this type of flight regime.
Flapping-wing flight is enjoying a resurgence of interest lately as robotics and biomimetics boffins seek to duplicate the various feats that birds and bugs perform easily yet which tend to stymie more conventional airframes such as small unmanned helicopters or planes. Examples include manoeuvres in confined spaces and accurate landings on tiny perches.
US company Aerovironment, for one, is known to be working on a so-called Nano Air Vehicle, thought to use flapping wings, for use by the US military. The new Japanese butterfly research could make such machines simpler and cheaper to build.
Tanaka and Shimoyama publish their research today in the journal Bioinspiration and Biomimetics. ®
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