The Engineering Book: From the Catapult to the Curiosity Rover: 250 Milestones in the History of Engineering

2012

Human-Powered Helicopter

Todd Reichert (Dates Unavailable), Cameron Robertson (Dates Unavailable)

Back in 1980, the excitement around human-powered aircraft was intense. An engineering marvel named the Gossamer Condor claimed the Kremer Prize (see “Human-Powered Airplane”) in 1977 with a figure-eight flight. In 1979, the seemingly impossible happened—Bryan Allen peddled the Gossamer Albatross 22 miles (35 km) across the English Channel in 169 minutes.

So in 1980, when the American Helicopter Society announced the Sikorsky Prize, it seemed relatively straightforward. The winner would need to rise to a height of 3 meters with human power alone and hold the craft there for 60 seconds. The flight could even be indoors to eliminate the wind.

It would take engineers more than three decades to claim this seemingly simple prize. A big part of it is the fact that a helicopter that is hovering takes a lot more power than an airplane that is flying. The Gossamer Albatross took 0.4 hp (300 watts) to fly straight and level. It is said that the pilot of the human-powered helicopter trained so that he could output more than one hp (750 watts) for several minutes. He could peak at 1.5 hp (1,100 watts) to initially get off the ground. This would be enough power for takeoff, the 60-second hover, and landing.

The Atlas helicopter uses four rotors, with the pilot sitting in the center. Each rotor is 33 feet (10 meters) in diameter. The total of eight wings and four hubs is itself expensive in terms of weight. Then the rotors must link together. This requires a massive X-shaped truss structure made of thin carbon fiber tubes and Vectran (a polymer) bracing lines. Once assembled, the helicopter is a 154 feet (47 meters) across, but weighs only 122 pounds (55 kg). Instead of heavy chains to power the rotors, the hubs are wound with thin Vectran lines. When the pilot pedals, he is spooling in four lines from the four hubs. So flight duration is limited by the length of those lines.

On August 28, 2012, Todd Reichert and Cameron Robertson, working with a team from the University of Toronto, powered the Atlas Helicopter and won the Sikorsky prize—32 years later.

Aerial view of the AeroVelo Atlas Human Powered Helicopter (HPH) developed for the AHS Sikorsky Prize. Taken from the “crow’s nest” of the Ontario Soccer Center.