The Aerodynamics of a Bee

In 1934, French entomologist Antoine Magnan famously proclaimed that, despite overwhelming evidence to the contrary, it was "impossible" doe bees to fly - they were too heavy, their wings too stubby. Magnan's error stemmed from his assumption that bees use the same aerodynamic principles that govern fixed-wing flight. Yet scientists had been unable to analyze more-complex types of flight, such as flapping or rotating wings, because synchronized high-speed cameras and robotic insect substitutes were not available until very recently.

But biomechanists Doug Altshuler of the California Institute of Technology and his team have now debunked the Magnan myth once for all, using three synchronized 6,000-frame-per-second digital cameras to dissect the flight of hovering bees. Their photographs and sensing equipment reveled that each time a bee's oar-like wing beats (about 230 a second), it forms a swirling vortex in the air directly above it.

This "leading edge" vortex keeps the airflow bound to the wing at steep angles of attack - conditions that would otherwise cause the bee to lose lift.

Bees can also change the length of their wing strokes to generate extra power. Another study found that when bees were carrying pollen, for instance, they beat their wings through an arc of 120 degrees instead of the usual 90 degrees. The extra power is particularly useful given bees' relatively high body weight with respect to their wing length. "It's almost like a menu, with every wing stroke, they can select a different option," Altshuler says. He envisions bees' flight secrets being used to design small reconnaissance and medical recovery vehicles.