July 15, 2013
It took 33 years, but perhaps the final great feat of human endeavor in aviation has been accomplished, with Canada's AeroVelo team winning the $250,000 Sikorsky prize for human-powered helicopter flight, offered by the American Helicopter Society (AHS) International.
Piloted and powered by Todd Reichert, AeroVelo's Atlas flew for 65 sec., reaching a height of 3.3 meters (10.8 ft.) and staying within a 10-meter box to win the prize. The flight took place June 13 at an indoor soccer center in Vaughan, Ontario. The University of Maryland's (UMD) Gamera team completed flights of its human-powered helicopter (HPH) on June 26 without fulfilling the requirements, but set an unofficial duration record of 74 sec.
“This was not about creating a practical helicopter,” says AHS Executive Director Mike Hirschberg. “It was intended to challenge engineers in the vertical flight community to harness a variety of technical skills and work as a team to meet stringent technical requirements.”
Inspired by Paul MacCready's Gossamer Condor winning the Kremer prize for human-powered aircraft flight in 1977, the HPH competition was established by AHS in 1980 after a study showed it was feasible—in theory. Named after helicopter pioneer Igor Sikorsky, the prize initially was just $10,000. But the competition heated up after 2009, when Sikorsky Aircraft pledged $250,000 for the prize.
To win, an HPH had to hover for 60 sec., reach 3 meters altitude and stay within a 10-meter box. Duration was set to “approach the limits of human endurance,” and required efficient power extraction and transmission. The height goal emphasized maximizing lift and minimizing weight, while the drift limit put a premium on controllability. “It took a third of a century of aerospace development—and a significantly larger prize—to make it realizable,” Hirschberg says.
Gordon Leishman, a professor in rotorcraft at UMD, considered the prize “all but impossible to win.” Looking at the study that set the rules, he saw “the most wildly optimistic assumptions” and concluded “there was no way anybody could do this.” Tipping his hat to both teams, he says “the science behind this means they had to get everything right.”
The first HPH to fly was California Polytechnic State University's Da Vinci III, which hovered for 8.9 sec. in 1989, while in 1994 a Japanese team at Nihon University flew the Yuri I HPH for 19.46 sec. Where Da Vinci had a single reaction-drive rotor, Yuri was a quadrotor—a stable configuration later adopted for Gamera and Atlas.