Solving the Mystery of Insect Flight; June 2001; Scientific American Magazine; by Michael Dickinson; 8 Page(s)
In a two-ton tank of mineral oil, a pair of mechanical wings flap continuously back and forth, taking a leisurely five seconds to complete each cycle. Driven by six computer-controlled motors, they set the fluid swirling, a motion that is revealed by millions of air bubbles immersed in the liquid (the tank has a strong resemblance to a giant glass of beer, albeit one with a 60-centimeter-wingspan mechanical fly thrashing around in it). Flashing sheets of green laser light illuminate the scene, and specialized video cameras record the paths of the glistening, churning bubbles. Sensors in the wings record the forces of the fluid acting on them at each moment.
My research group constructed this odd assortment of specialized equipment to help explain the physics of one of the commonest of occurrences-the hovering of a tiny fruit fly. The fly knows nothing of the aerodynamics of vortex production, delayed stall, rotational circulation and wake capture; it merely employs their practical consequences 200 times each second as its wings flap back and forth. The fly's mechanical simulacra, dubbed Robofly, imitates the insect's flapping motion, but at a thousandth the speed and on a 100-fold larger scale. Awed by the rapidity and the small size of the real thing, my colleagues and I pin our hopes on Robofly for understanding the intricate aerodynamics that allows insects to do what they do so routinely-that is, how they are able to fly.