The Flight of Dragonfly Robots

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In terms of four-wing versus two-wing systems for a biomimetic micro air vehicle, "it's a trade-off," says Fritz-Olaf Lehmann, a researcher at the University of Ulm who worked on the study. With a four-wing system, the disadvantages are the need for an extra control system and extra power. However, a system with two wings must incorporate ways to change the angle, amplitude, and frequency of the wings flapping to change lift, says Lehmann. Conversely, with four wings, "you can just advance one flight system against the other, and then you change lift production," he says. "I think that makes building a micro air vehicle much easier."

In creating an autonomous micro air vehicle, "every little bit of efficiency counts," says Robert Wood, a professor at Harvard University who has developed some of the smallest flying robots. "You could make the argument that if you have a four-winged vehicle, you'll have more [control] to assist you in stabilization," he says.

Michael Dickinson, a professor at Caltech who works on understanding and mimicking fly flight, says that interest in dragonflies is growing and that the Lehmann paper is not the first containing this kind of analysis but "one in a floodgate of papers." While the study might add to the understanding of the subtle aerodynamics of four-winged flight, Dickinson points out that researchers must still develop a better, lighter battery that powers the vehicle and makes an effective control system.