June 26, 2012 3:08 pm
Kyle Gluesenkamp powers the Gamera II helicopter
A team of engineering students designed and built a bicycle-powered helicopter that managed to hover just above the ground for 50 seconds—10 seconds and 3 meters of altitude shy of the $250,000 Igor. I Sikorsky Human Powered Helicopter Competition prize.
The aircraft consists of a stable X-shaped frame with rotors of 13 metres diameter installed at the end of each 18-metre arm. Crafted from carbon fibre, mylar plastic, balsa and foam, the aircraft comes in at around 32kg. However, despite pedalling ferociously during the record-breaking test flight, the pilot — mechanical engineering student Kyle Gluesenkamp — does not appear to come close to the three-metre altitude rule.
For the mathematically inclined, physicist-blogger Rhett Allain walks through the mechanics of bicycle flight:
Let’s say that you want a smaller huma-copter. Say you want to use a rotor area that is half the size of the one above. To compensate for the smaller rotor, you will need to push the air faster – faster by a factor of the square root of 2. Fine. But now, what about the power? Since the power depends on area and the air speed cubed, this will take 40% more power. When you are at the limit of human power output, 40% can make a big difference.
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