Engineering design solutions draw inspiration from many sources. For example, did you know that the Wright brothers were bird watchers and that they modeled their airplane wing after a bird's wing? Biomimicry, a word derived from bios, meaning "life," and mimesis, meaning "to imitate," refers to the study of nature's most successful developments and the imitation of natural designs and processes in the solving of human problems.

The ability to control an unpiloted aircraft from remote locations offers numerous advantages. Unmanned aerial vehicles (UAVs) can fly at higher altitudes for longer time periods than can piloted craft, and they can perform high-speed evasive maneuvers, the forces of which would stretch a person beyond his or her physical limitations. In certain difficult phases of flight, such as low-level night flying over uneven terrain or bad-weather landings, computerized control systems are able to maneuver aircraft more reliably than manual systems can. However, a UAV's size and fixed-wing design limit its ability to perform certain military objectives such as spying, as well as to collect data and perform certain commercial functions.

Using insights gained through observing insect flight, aeronautical engineers have designed a class of miniature unmanned aerial vehicles (MAVs) that may overcome these limitations. Scientists have found insect flight to be a good motion to mimic for several reasons. Flapping wings allow insects and birds to take off and land in a standing position, fly at low speeds, hover, make sharp turns, and even fly backward. The physical limitations of fixed-wing designs prohibit conventional aircraft from doing any of these things.

Fixed-wing and flapping-wing designs differ in how they create lift. Fixed-wing aircraft rely on lift generated by the vehicle moving through the air. Because lift is directly proportional to wing area and the velocity of air flow over the wing, the smaller the wings, the less lift they can supply. Most aircraft designs counter this effect by increasing the velocity of the vehicle. By contrast, a flapping-wing design relies on lift generated by both vehicle speed and wing flapping. So, if engineers wanted a smaller aircraft to fly, they would only need to increase the frequency of the flapping to keep the aircraft aloft.

In addition to military reconnaissance, MAVs could be used in search-and-rescue missions and for mapping dangerous areas, such as the interiors of collapsed buildings. MAVs could also assist in traffic reporting, wildlife surveys, and scores of other applications.

Explore some of the challenges associated with building extremely small aircraft in this NOVA classroom activity.

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