London, May 20 (IANS) Japanese researchers have built a fully functional replica of a swallowtail butterfly or ornithopter and they have filmed it in flight.

Among the various types of butterflies, swallowtails are unique as their wing area is very large in relation 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, said a release of the Institute of Physics, UK.

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.

These findings were published in Bioinspiration & Biomimetics.