High-Speed Video Shows How Flies Change Direction So Quickly

Fruit flies turn in midair with a shrug of their shoulders. A new analysis shows that the flies’ aerial gymnastics are driven by wing joints that act like wind-up toys, letting the bugs whirl around almost automatically. The insights could someday help build better flying robots.

Fruit flies beat their wings about once every 4 milliseconds — much faster than their neurons can fire — and can turn 120 degrees in 18 wing beats.

The researchers set up three high-speed cameras trained at the center of a box holding about 10 flies (see video below). A fly crossing the center of the box triggered the cameras to start rolling at 8,000 frames per second. At the same time, a disk of LED lights projected a rotating striped pattern on the inside of the box to trick the flies into making a U-turn.

The team found that when the fly turns, one wing tilts more than the other, similar to the way a rower pulls one oar harder than the other to make a boat turn. Thanks to aerodynamics, a wing-tilt difference of just 9 degrees is enough to send a fly off in another direction.

Further analysis using computer models of the fly and aerodynamic simulations showed that the fly’s wing joint acts like a torsional spring, the kind found in wind-up toys or old clocks. To change its wing tilt and set up a turn, all the fly has to do is twitch the muscle that controls the spring.



Original article here.