University of Maryland students close in on the human-powered helicopter prize.
- By Paul Glenshaw
- Air & Space magazine, January 2013
It was difficult to take in all at once: Four giant Mylar-covered rotors the size of windmill blades rotated, fishing line winding around a spool plinked like an untuned toy harp, and a vast, spidery structure trembled with the effort of a madly pedaling figure at its center. The pedaling figure turned the spool that wound the fishing line that worked the pulleys that drove the rotor blades. Late in the afternoon of May 4, 2011, no one was breathing in the University of Maryland gym.
I looked over at my 16-year-old son Tim. He had the camera on, capturing video. We’d first read about the machine that morning in the newspaper: a human-powered helicopter named Gamera (after a Japanese movie monster). We had dashed over, as soon as Tim got out of school. The article said that the team of students and faculty advisers who created Gamera were that day making their first attempts to fly, and right now, this very unusual helicopter was trying like hell.
At the center of the vehicle, near the cockpit, four students crouched, each one watching one of the four rotors intently, waiting to signal liftoff. First one hand went, then two more, then the fourth. The machine bobbed and inched itself off the gymnasium floor. For 4.2 seconds, everyone was transfixed. The pedaling slowed, the craft settled down, and the team went nuts—cheering, hugging, and spraying cheap champagne. Although they knew they were nowhere close to winning the prize they were aiming for, they had started. They could fly.
Gamera is not the first human-powered helicopter to do so. Others have tried, but very few have left the ground. All were in pursuit of the $20,000 Sikorsky Prize, first announced in 1980 by the American Helicopter Society and sponsored by Sikorsky Aircraft. To win, a machine must fly at least 60 seconds, reach an altitude of three meters (9.8 feet), and stay within a 10-meter (32.8-feet) square box—powered only by a single human.
Unlike fixed-wing aircraft, helicopters can’t produce lift without power. From one perspective, for a helicopter, a human is the worst conceivable source of power; a human being can barely generate enough oomph to offset his or her weight. But for those chasing the prize, that low power output makes the engineering all the more exciting. Solving the three fundamental design problems inherent in a human-powered helicopter requires extraordinary ingenuity. The design must maximize lift. With the low-power engine, small, high-speed rotors are impossible—so the machine will be large, with big, slow-turning rotors. The rotors must take maximum advantage of their position very close to the ground to reduce as much as possible the amount of power needed to leave it. The airframe must be strong enough to support itself and the weight of its human engine. Most critically, it must be extremely light.
In 1989, the first successful human-powered helicopter flight was made in a machine named Da Vinci III, built by a team at the California Polytechnic State University in San Luis Obispo and led by student Neal Saiki. The flight lasted eight seconds. The next milestone was reached at Nihon University in Japan, under the guidance of Akira Naito. In 1994, Naito’s Yuri-I left the ground for an astonishing 19.4 seconds. Fourteen years later, Gamera was born in College Park, Maryland.
In 2008, University of Maryland professor Fred Schmitz posed the high-weight/low-power feasibility of a human-powered helicopter to students as part of an exam, then raised the long-dormant Sikorsky Prize for discussion at a lunchtime meeting with his colleagues. Everyone had known about the prize for years, and knew of the previous attempts. Inderjit Chopra, head of the university’s rotorcraft center, had even experimented with models 30 years before. But a lot had changed, especially with computer-assisted design tools and simulations. Even the prize itself had changed: It is now worth $250,000.
Despite justifiable skepticism from several faculty members, Darryll Pines, then chair of the aerospace department, saw an opportunity, given a prevailing characteristic of Maryland students. “They have a slight chip on their shoulder,” says Pines. “They are as good [as students at other more prestigious universities], and they’ll work even harder, and they’ll beat you.” Pines has observed over the years that many of his engineering students labor to prove that they are as talented as the students at Ivy League schools. He cites their 2011 first place in the Solar Decathlon competition, beating out universities from around the nation and globe in building an affordable, efficient solar house. So he and the advisers appealed to that sense of pride: “We asked, ‘Do you want to be part of something really special: a first in flight? Why not us?’ ”
A large and enthusiastic group of students quickly coalesced around the quad-rotor design, similar to Yuri-I. Working mostly under wraps for the next two years, the team ran a series of tests investigating materials, structures, and performance, and based on results, designed the machine with several innovations: They invented “baby” trusses—both lighter and stronger than standard, off-the-shelf carbon-fiber tubes—to make up a significant portion of the larger structure. They created rotors that provide more total area than Yuri-I. And they gave the pilot/engine pedals to work with both hands and feet, instead of with feet alone. The goal at this stage was to simply get off the ground.
Virtually the only word that went out before Gamera’s first flights was a notice, posted around campus, advertising for pilots. Several hopefuls responded, but most were too big. Judy Wexler, Kyle Glusenkamp, and Colin Gore fit the bill: All weighed 135 pounds or less. All were competitive cyclists. Their training directive was simple: Pedal as fast and as long as you can.
In May 2011, after thousands of student hours and months of construction, Wexler muscled the giant fledgling into the air for the first time. It was a close call, both aerodynamically and logistically. To set up, assemble, and hope nothing went terribly wrong, the team had acquired permission to use the gymnasium for only a few days. The flight happened in the closing hours of their last day.
In July, the team got an opening to fly at the university’s armory building, and experienced their first crash. One of the transmission lines slipped off its pulley, a rotor lost lift, and Wexler came down—hard. She was fine, but Gamera’s trusses were mangled. A crew worked through the night to repair the vehicle. The next day, July 13, Wexler smashed her own record, going 11.4 seconds. As in May, an official observer from the National Aeronautic Association was present. Gamera officially became the human-powered helicopter world record-holder (Yuri I had had no official observer).
As satisfying as the recognition was, the real lesson was in the crash, and the team’s ability to respond. “The first time we crashed, we were heartbroken,” says Will Staruk, a lead student engineer. “The last time, no one cared, because we’ve never been stopped by something like that.” The students were gaining experience in what most aeronautical engineers dream of doing: flight testing.