Humanity has solved the challenge of flying in many ways, but there’s a niche little known to the public: the human-powered aircraft. And, the most niche of the niche, the greatest challenge of all, the human-powered helicopter!
Helicopters are all about brute force. When it comes to rotors, there’s no equivalent to the glider. In 1980, the American Helicopter Society created the Sikorsky Prize for the first human powered helicopter, which required the flight to last 60 seconds at an altitude of 3 metres (9.8 feet), with the centre point of the aircraft hovering over a 10-by-10- -metre (33 by 33 ft) area. In 2009, the prize money was increased to $250,000. It took a full 33 years to be claimed.
The performance of the University of Maryland’s Gamera I inspired the Canadians at AeroVelo (University of Toronto) to give it their best. The Maryland students then created Gamera II, which flew for 65.1 seconds inside the square, but without managing the required altitude. The Canadians took a completely different approach: instead of adapting the size of the helicopter to the available flight site, they adapted it to the power source, a 78-kilo human. The result was the Atlas, the world’s second biggest helicopter, with wings broader than an Airbus 320. The quadrotor configuration was chosen for having no torque, avoiding the use of the inefficient tail rotor.
AeroVelo team combined computational simulation and experimental tests until they had a prediction range of 5%, the optimum efficiency of rotor size and structural weight. They added top competition cycling components, while transmission was achieved by winding wires from the central bike to each of the rotors. These were the same shape as the wings of the Gossamer Albatross, a “human” aeroplane that crossed the English Channel in 1979, using carbon fibre tube spar and balsa and polystyrene ribs, covered with Mylar.
The Atlas flew inside a football stadium for the first time on 28th August 2012. 75 flights were still needed, with various crashes and accidents, before the prize was lifted on 13th June 2013. On that final flight, the average power was 700 watts, or approximately 10,000 calories, or two kilos of chocolate…
by Ricardo Reis
web design & development 262media.com