A group of Japanese researchers, who publish their findings today Thursday, 20 May in IOP Publishing's Bioinspiration & Biomimetics（生物模仿学） , have succeeded in building a fully functional replica（复制品） model – an ornithopter（扑翼飞机） – of a swallowtail butterfly（燕尾蝶） , 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（重叠，覆盖） 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（气动力） 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（气体力学） .

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（薄膜，细胞膜） and veins that cover its wings.

Using motion analysis software, the researchers were able to monitor the ornithopter's aerodynamic（空气动力学的） performance, showing that flight can be realised with simple flapping motions without feedback control（回馈控制） , a model which can be applied to future aerodynamic systems.