To facilitate a better understanding of the aerodynamic forces generated by flies, the team built a huge model of the wings of a fruit fly. Aptly dubbed “Robofly,” the device mimics the atmospheric effects of a fruit fly’s 1 mm wings flapping in the air. In order to quantify the aerodynamic forces acting on the insect’s wings, the team also constructed (and immersed in a 2-ton tank of mineral oil) a 15 in. dynamically scaled robotic wing, which flaps and rotates at one-hundredth the rate of an actual fly’s wing. Six motors move the robotic wing back and forth in precise, computer-controlled motions. Air bubbles pumped into the tank indicate the aerodynamic flow patterns on the wing, and sensors measure the wing’s forces during each phase of its motion.

Using these unique instruments to dissect the complex aerodynamics of fruit fly motion, Dr. Dickinson determined that a fruit fly executes a series of wing motions in order to turn. The fly first generates sufficient torque to accelerate into the turn. As it nears its desired turn angle, the fly then actively counteracts its own rotational inertia by producing torque in the opposite direction, thus halting the rotation of its body. Once the fly has achieved its desired turn angle, it then buzzes flawlessly through the turn and off in another direction. “They’re arguably the most aerodynamically sophisticated of all flying animals,” Dr. Dickinson asserts.

Although the researchers performed these experiments on tiny fruit flies, they speculate that their results will help scientists understand the flight dynamics of nearly all insects, particularly since the important balance of inertia and friction changes according to the size of the insect. Dr. Dickinson’s research results also provide insight into the design of biomimetic flying devices, which could prove beneficial to future military operations

Lt Col Sharon A. Heise and Mr. John Malthaner, of the Air Force Research Laboratory’s Air Force Office of Scientific Research, wrote this article. For more information, contact TECH CONNECT at (800) 203-6451 or place a request at http://www.afrl.af.mil/techconn/index.htm. Reference document OSR-H-05-04.