Small instrumented, free-flying (unpowered) rotary aircraft have been proposed for use in gathering scientific data from hazardous or inaccessible terrain on remote planets as well as on Earth. These aircraft are called "seed-wing flyers" because they would resemble winged seeds (e.g., maple seeds) in both appearance and aerodynamic behavior.
The class of seed-wing flyers would constitute a subset of biomorphic explorers — mobile exploratory robots, inspired by natural biological forms, that would be equipped with microsensors and associated electronic circuits (including communication circuits). Biomorphic explorers and related concepts have been described in several previous articles in NASA Tech Briefs, the most relevant being "Biomorphic Explorers" (NPO-20142), Vol. 22, No. 9, (September 1998), page 71; "Earthwormlike Exploratory Robots" (NPO-20266), Vol. 22, No. 6, (June 1998), page 11b; "Insectile and Vermiform Exploratory Robots" (NPO-20381), Vol. 23, No. 11, (November 1999), page 61; and "Biomorphic Gliders" (NPO-20677), Vol. 25, No. 4 (April 2001), page 65. Seed-wing flyers could be dropped in large numbers over the terrain of interest from aircraft, spacecraft, or perhaps other biomorphic flyers. The dropped seed-wing flyers would then descend, spread out, and land at numerous locations on the terrain.
The flight of a winged seed is characterized by autorotation: The aerodynamic forces on the wing cause the wing and the rest of the seed to rotate in such a way as to generate lift, which retards descent. A winged seed or an artificial object shaped like a winged seed is as effective in retarding descent as is a parachute with a radius equal to the wing span. The underlying aerodynamic principle is essentially the same as that of helicopters and autogyros.
Seed-wing flyers would be perhaps the simplest of all artificial flight systems in that like natural winged seeds, they would contain no moving parts, no control systems, and very few structural elements. In the intended application, seed-wing flyers would be used as alternatives to instrument packages dropped with parachutes. As in the case of parachutes, payload mass fractions could be large — greater than 80 percent in some cases. Seed-wing flyers would afford some advantages over parachute-dropped instrument packages, including the following:
- Unlike a parachute-dropped instrument package, a seed-wing flyer would have an unobstructed overhead view; in a situation in which there was a need to measure solar irradiance, such a view would be essential.
- A seed-wing flyer could be built from relatively few parts.
- A seed-wing flyer could be deployed reliably by simply dropping it; in contrast, deployment of a parachute entails a substantial deployment mechanism.
- At least on a small scale, a seed-wing flyer would likely be less massive than would be a parachute-dropped instrument package of similar functionality.
This work was done by Sarita Thakoor of Caltech and Carlos Miralles of Aero- Vironment for NASA's Jet Propulsion Laboratory. For further information, access the Technical Support Package (TSP) free on-line at www.nasatech.com/tsp under the Physical Sciences category.
This Brief includes a Technical Support Package (TSP).
Seed-Wing Flyers for Exploration
(reference NPO-20676) is currently available for download from the TSP library.
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