Page 274 - The Origin of Birds and Flight

272 The Origin of Birds and Flight

AERODYNAMICS IN A BUTTERFLY’S WINGS
Researchers from Great Britain’s Oxford University developed a new
technique in order to study butterfly flight. They found that butterflies do
not beat their wings at random, but actually use far more flight tactics than
had previously been supposed.
Researchers from Cambridge University in England, on the other
hand, observed that wing movements of peacock butterflies establish a
vortex on the farthest extremity of the wing that enables the insect to rise
in the air. According to Robert Srygley, a professor of behavioral ecology
at South Korea University and also a researcher at Oxford University, in-
vestigations have shown that butterfly flight is far more complex:
Free-flying butterflies use all of the known mechanisms to enhance lift—
wake capture, leading-edge vortex, clap and fling, and active and inac-
tive upstrokes—as well as two mechanisms that had not been postulat-
ed, the leading-edge vortex during the upstrokes and the double leading-
edge vortex. 241
To make sudden changes in their altitude, butterflies establish vor-
texes and double vortexes at the extremities of their wings by changing the
rotation and speed of their wing beats, and use different aerodynamic
stages in consecutive wing movements. According to Robert Srygley, the
apparently random fluttering of butterflies is actually a series of different