In today's issues of Bioinspiration & Biomimetics, a group of Japanese researchers report that they built a replica of a swallowtail butterfly and, filming it in flight, the artificial ornithopter proved that flight can occur without certain aerodynamic conditions.
The swallowtail, a lovely large ornithopter, does not fly by aerodynamic force, because its fore-wings partially overlap its hind-wings, which restricts the feathering that's required for aerodynamic flight. Researchers Hiroto Tanaka and Isao Shimoyama from Harvard University and the University of Tokyo, respectively, built an artificial butterfly to support their hypothesis that because the feathering activity does not provide enough aerodynamic feedback (to lift the butterfly's body), the swallowtail must therefore use its flapping motions to fly.
To test this theory, the researchers let the artificial butterfly fly! And they filmed it with a high-speed video camera, allowing them to see that indeed the butterfly's body could achieve forward flight by moving up and down passively in synchonization with its flapping.
Thus, the lessons learned from the biomimetic swallowtail butterfly can be applied to future aerodynamic systems.