The Physiology of Human-Powered Flight

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The physiology of human-powered flight

When bicyclist-cum-pilot Kanellos Kanellopoulos pedaled an aircraft 74 miles across the Aegean Sea in April 1988, breaking the previous record for self-powered time aloft, the engineers who designed the craft garnered a hefty dose of praise (SN: 4/30/88, p.277).

Less publicized, however, was a stunning success story about the application of theoretical physiology to a practical task. Out of the limelight, a team of metabolic mechanics put in long hours figuring how to keep Kanellopoulos' human-body engine perfectly fueled and tuned during the strenuous four-hour trip.

The so-called Daedalus 88 flight provided a wealth of information about the physiological adjustments required for human-powered flight, reports Ethan R. Nadel, a physiologist at Yale University who helped perform the computations that went into keeping the pilot airborne. Most critical was the need to sustain a constant energy output that would keep the plane moving at the 15- to 17-mph airspeed required to stay at altitude. With the plane designed to fly only 12 to 15 feet above the sea, even a brief loss of energy could spell disaster.

Using measurements taken from ground-based bicyclists, Nadel and his colleagues calculated the amount of adenosine triphosphate--the ultimate energy source in skeletal muscle--required to produce the 3 to 3.2 watts of mechanical output per kilogram of pilot weight that the plane was designed to use. …