UMD flew the Gamera II in June 2012, setting a record for flight duration of 49.9 sec. piloted by Kyle Gluesenkamp. In August and September, the team tested a refined aircraft, staying aloft for 65 sec. on one flight and reaching a height of 9 ft. on another. The Gamera II XR has 70-cm longer blades and foam-shell outboard blade sections to maintain airfoil shape. These and other modifications increase power and lift, but add about 6 lb. to the weight.
AeroVelo began flying the Atlas in August 2012, piloted by Reichert, and has routinely exceeded 30 sec. as it tests modifications to trim the vehicle and controls. A few issues remain to be ironed out, but “we know the power requirements of the helicopter are reasonable for the pilot and the controls will be sufficiently effective during the Sikorsky flight,” says Robertson. All three contenders drift in flight, making it difficult to stay within the 10 x 10-meter box to win the prize, but only the Atlas has manual flight control.
With the pilot using both hands and feet to power the aircraft, UMD faced a challenge developing a control system for the Gamera II. But an attempt to clarify the rule prohibiting energy-storage devices inadvertently opened the door to electronic controls being used on both the Gamera II and Upturn II.
AHS has closed the loophole, but both teams have until July to attempt winning the prize under previous rules. UMD tested a control system based on center-of-gravity shifting in November 2012, but it added too much weight. A new control system has been developed, but kept secret. “However, our reading of the rules does suggest that an electric system would only be allowed if the pilot were to generate the electricity used during the flight,” says project manager William Staruk.
Human-powered flight may seem a far cry from practical everyday aviation, but Kremer prizewinner MacCready founded AeroVironment, now a leading supplier of unmanned aircraft, while Langford formed Aurora Flight Sciences.
After the success of the Gossamer Condor and Albatross, AeroVironment developed two solar-electric aircraft. The Gossamer Penguin flew in 1980, and in 1981 the Solar Challenger made a 163-mi. flight from France to England. The company then developed a series of solar-powered stratospheric UAVs, first secretly for the Pentagon, then for NASA, with the 100-ft.-span Pathfinder reaching 71,500 ft. in 1997 and the 247-ft.-span Helios achieving a record altitude of 96,863 ft. in 2001.
AeroVironment found fame making small hand-launched UAVs, but returned to its origins in aerodynamic and structural efficiency with the hydrogen-powered Global Observer. Designed to fly for a week at up to 65,000 ft., the 175-ft.-span UAV flew in August 2010, but crashed in April 2011.
Aurora was formed a year after MIT's Daedalus set human-powered endurance and distance records with the idea of finding practical applications for the technology. The first of these was the Perseus gasoline/liquid-oxygen-powered high-altitude UAV built for NASA to perform climate research.
Aurora returned to its roots to build the hydrogen-powered, high-altitude Orion, which never flew, but instead morphed into a diesel-powered medium-altitude, long-endurance UAV—work on which has been stalled by lack of funds. But closest to the company's origins was its design work on the U.S. Defense Advanced Research Project Agency's now-defunct Vulture program to develop a solar-powered stratospheric UAV capable of staying aloft for five years.