New Generation of Energy-Efficient UAVs Published Sept. 18, 2009 By Molly Lachance Office of Scientific Research ARLINGTON, Virginia -- Driven by ever-increasing military demands to reduce unmanned air vehicle size and weight but lengthen flight times, Air Force Research Laboratory is funding a project exploring the integration of solar power sources directly into the base materials used to build UAVs. Dr. Max Shtein and his team of lab-sponsored University of Michigan researchers are investigating the energy harvesting potential of many different device applications, including one that employs thin-film solar cells reshaped and applied as a coating to long, continuous filaments, or fibers. When woven into a fabric system, such organic, semiconductor-coated fibers produce textile suitable for the UAV's structural makeup and, further, capable of generating its electrical power. To date, Dr. Shtein and his team have demonstrated small, stand-alone prototypes that strongly suggest the feasibility of this application type. Integrating the solar cells into the desired configuration, however, will require that more sophisticated fabrication equipment be constructed. Meanwhile, work is continuing on a customized coating apparatus for making large quantities of fiber-based energy conversion devices. Upon the completion of this apparatus, Dr. Shtein plans to develop new models combining optics, mechanics, electrical and energy transport, and energy storage mechanisms. These synergistic models will enable the optimization of device structure via multifunctional design constraints, improving both energy conversion efficiency and power density in practical configurations. This integration of multiple functionalities will also reduce the bulk mass associated with separate optical, mechanical, and electrical systems, facilitating vehicles with increased power but much less weight. UAVs constructed with these novel materials would be light and compact. In addition, their built-in, renewable energy source would extend flight times by providing power for propulsion systems and onboard sensors, greatly benefiting the Air Force as a result. Having recently earned the Presidential Early Career Award for Scientists and Engineers for his notable contributions, Dr. Shtein will receive grant funds totaling $200,000 a year for 5 years towards advancing this innovative work.